Hi
I get this error:

"collection foreign key mapping has wrong number of columns: data.Tests.PartId type: Tests"

but I don't understand the meaning of it?

I just use a one-to-many mapping:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="data.Tests,data" table="Tests">

<composite-id>
<key-property name="FKPartId" column="PartID" />
<key-property name="TestOrderId" column="TestOrderID" />
</composite-id>
<property column="TestID" type="Guid" name="Testid" not-null="true" />


<set
name="PartId"
inverse="true"
cascade="all-delete-orphan">
<key column="PartID"/>
<one-to-many class="data.Parts, data"/>
</set>
<set
name="BinaryTestid"
inverse="true"
cascade="all-delete-orphan">
<key column="BinaryTestID"/>
<one-to-many class="data.BinaryTest, data"/>

I hope someone can help :)
Cheers
</set>

</class>
</hibernate-mapping>