Stack trace of death:

hibernate exception occured
net.sf.hibernate.PropertyValueException: not-null property references a null or transient value: net.gumb.datatypes.auction.seller
at net.sf.hibernate.impl.SessionImpl.checkNullability(SessionImpl.java:1277)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:928)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:857)
at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:775)
at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:738)
at net.sf.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:1388)
at net.sf.hibernate.engine.Cascades$4.cascade(Cascades.java:114)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:436)
at net.sf.hibernate.engine.Cascades.cascadeCollection(Cascades.java:526)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:452)
at net.sf.hibernate.engine.Cascades.cascade(Cascades.java:503)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:952)
at net.sf.hibernate.impl.SessionImpl.doSave(SessionImpl.java:857)
at net.sf.hibernate.impl.SessionImpl.saveWithGeneratedIdentifier(SessionImpl.java:775)
at net.sf.hibernate.impl.SessionImpl.save(SessionImpl.java:738)
at net.gumb.service.dynPxImpl.doSomething(dynPxImpl.java:103)
at dynPxService.doSomething(dynPxService.java:25)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.apache.axis.providers.java.RPCProvider.invokeMethod(RPCProvider.java:402)
at org.apache.axis.providers.java.RPCProvider.processMessage(RPCProvider.java:309)
at org.apache.axis.providers.java.JavaProvider.invoke(JavaProvider.java:333)
at org.apache.axis.strategies.InvocationStrategy.visit(InvocationStrategy.java:71)
at org.apache.axis.SimpleChain.doVisiting(SimpleChain.java:150)
at org.apache.axis.SimpleChain.invoke(SimpleChain.java:120)
at org.apache.axis.handlers.soap.SOAPService.invoke(SOAPService.java:481)
at org.apache.axis.server.AxisServer.invoke(AxisServer.java:323)
at org.apache.axis.transport.http.AxisServlet.doPost(AxisServlet.java:854)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
at org.apache.axis.transport.http.AxisServletBase.service(AxisServletBase.java:339)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:300)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:374)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:743)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:675)
at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:866)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Thread.java:534)

Mapping Doc:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="net.gumb.datatypes.seller" table="sellers">
<!-- automatically generated primary key for this class -->
<id name="id" type="integer">
<generator class="native"/>
</id>

<!-- the ebay username of this particular seller -->
<property name="username" column="username" type="string" />
</class>

<class name="net.gumb.datatypes.bidder" table="bidder">
<!-- automatically generated primary key for this class -->
<id name="id" type="integer">
<generator class="native"/>
</id>

<!-- the ebay username of this particular seller -->
<property name="username" column="username" type="string" />
</class>

<class name="net.gumb.datatypes.bid" table="bid">
<!-- automatically generated primary key for this class -->
<id name="id" type="integer">
<generator class="native"/>
</id>

<many-to-one name="bidder"
class="net.gumb.datatypes.bidder"
cascade="none"
column="bidder_id"
update="false"
not-null="true"
outer-join="false"
/>


<property name="bidvalue" column="bidvalue" type="currency" />
</class>




<!-- MARKET
class encapsulating a set of homogenous goods provided by sellers which buyers may place bids on
-->
<class name="net.gumb.datatypes.market" table="market">
<!-- automatically generated primary key for this class -->
<id name="id" type="integer">
<generator class="native"/>
</id>

<!-- search criteria for spider, words which return an appropriate list of auctions-->
<property name="name" column="name" type="string" />

<!-- unordered collection of auctions which represent individual products for sale in the market -->
<bag name="auction" table="auctions" cascade="all" inverse="true">
<key column="marketID"/>
<one-to-many class="net.gumb.datatypes.auction"/>
</bag>

</class>

<!-- AUCTION
class encapsulating a individual product offered for sale, and the interactions with different actors
which determine it's final price.
-->
<class name="net.gumb.datatypes.auction" table="auctions">
<!-- automatically generated primary key for this class -->
<id name="id" type="integer">
<generator class="native"/>
</id>


<property name="auctionNo" column="auctionno" type="string" />

<!-- wheather or not this auction has closed. -->
<property name="complete" column="complete" type="boolean"/>

<!-- associated class representing the seller of the product.-->
<many-to-one name="seller"
class="net.gumb.datatypes.seller"
cascade="none"
column="SELLER_ID"
update="false"
outer-join="false"
/>

<!-- list of bids which have been placed in this auction
with multiple bids by same bidder.-->

<bag name="bids"
cascade="all"
inverse="true"
lazy="true"
>
<key>
<column name="auction_id" not-null="true"/>
</key>
<one-to-many class="net.gumb.datatypes.bid"/>
</bag>


</class>




</hibernate-mapping>

and finally the code (like a test case almost):

try{
Session session = hibernateService.currentSession();
Transaction tx= session.beginTransaction();


seller sellr = new seller();
sellr.setUsername("Seller1");

bidder bidr1 = new bidder();
bidr1.setUsername("bidder1");
bidder bidr2 = new bidder();
bidr1.setUsername("bidder2");
bidder bidr3 = new bidder();
bidr1.setUsername("bidder3");

Currency cur = Currency.getInstance("EUR");

bid bid1 = new bid();
bid1.setBidder(bidr1);
bid1.setBidvalue(cur);
bid bid2 = new bid();
bid2.setBidder(bidr2);
bid2.setBidvalue(cur);
bid bid3 = new bid();
bid3.setBidder(bidr3);
bid3.setBidvalue(cur);
bid bid4 = new bid();
bid4.setBidder(bidr3);
bid4.setBidvalue(cur);

ArrayList bids1 = new ArrayList();
bids1.add(bid1);
bids1.add(bid2);
bids1.add(bid3);

ArrayList bids2 = new ArrayList();
bids2.add(bid4);

auction auc1 = new auction();
auc1.setAuctionNo("4312412412341");
auc1.setSeller(sellr);
auc1.setBids(bids1);

auction auc2 = new auction();
auc2.setAuctionNo("3423142142344");
auc2.setSeller(sellr);
auc1.setBids(bids2);

ArrayList aucs = new ArrayList();
aucs.add(auc1);
aucs.add(auc2);

market mkt = new market();
mkt.setName("sony camera");
mkt.setAuction(aucs);

session.save(mkt);

// session.save(mkt);
tx.commit();
HibernateUtil.closeSession();

logger.info("saved to db ok");


}
catch (HibernateException e){logger.info("hibernate exception occured"); e.printStackTrace();}
}

makes the exception of death at the top. what am i missing, been staring at this for hours. :<