Hibernate version: 3.1.2

I have a simple scenario which is giving me problems.

I have two mappings. A Company and a CompanyLogo. Right now, a company can only have one logo (this might change in the future), so here is my mappings:

<class name="Company" table="company">
<id name="companyId"
type="java.lang.Long"
column="company_id"
unsaved-value="0">
<generator class="native"/>
</id>

.... properties here ...

<one-to-one name="companyLogo"
class="CompanyLogo"
cascade="all"
constrained="true"
lazy="proxy"
property-ref="company">
</one-to-one>
</class>

<class name="CompanyLogo" table="company_logo" lazy="true">
<id name="companyLogoId"
type="java.lang.Long"
column="company_logo_id"
unsaved-value="0">
<generator class="native"/>
</id>

<many-to-one name="company"
class="Company"
column="company_id"
cascade="none"
not-null="true"
unique="true"
fetch="select"
index="idx_company_logo_company">
</many-to-one>
</class>

As you can see the CompanyLogo has it's own native primary key and has a many to one relationship with Company.

I tried the following code:

Company c = new Company();

... set properties ...

CompanyLogo l = new CompanyLogo();
l.setCompany(c);
c.setCompanyLogo(l);

... get session ...

ses.save(c);

This throws a null or transient exception on CompanyLogo.company...

If i change the company mapping from constrained="true" to constrained="false" it will work, but I want to keep it so that i have lazy support. In addition, a logo always exists for a company (just not always full of data).

Any have any ideas how I can get this working?

Thanks.