NullSafeSet is called with incorrect index

I've repeated my test with hibernate and java.
I've got much more descriptive error message:
Exception in thread "main" org.hibernate.MappingException: Repeated column in mapping for entity: hibtest.VirtualCardNumber column: number (should be mapped with insert="false" update="false")
instead of cryptic "Incorrect index" in NHibernate.
I've removed "Number" property which contains repeated column. There were no problems and test finished succesfully.
Then I've come back to test program in C#. It worked without a Number column correctly. Then I've returned to the bigger application I'm working on. There were also no problems.

Number property was obviously excessive. I can't explain why I couldn't remove it earlier.

Anyway issue can be closed.

I was a bit tired so it seemed that I've found a solution.
Actually I cannot delete property "Number" from mapping: "real" database raises an error: "property-ref [Number] not found on entity [DomainModel.VirtualCardNumber]"
From unknown reasons SQLite.NET doesn't issue this.
I'm attaching my small test project linked with SQLite.NET showing the issue.

May I close the issue?

I've found reason of the problem. Correct mapping is following:

<class name="Propertyref.VirtualCardNumber,Propertyref" table="virtualcardnumbers" lazy="true" mutable="false">
<id name="Serno" access="property" column="serno" type="int" unsaved-value="0">
<generator class="native" />
</id>
<property type="string" access="property" length="16" name="Vnumber" column="vnumber" />
<property type="string" access="property" length="16" name="Mnumber" column="mnumber" />
<many-to-one name="Card" cascade="none" column="number" access="property" property-ref="Number"/>

Additional data:
I've changed TString to standard string type. The Odbc error remains the same. I've verified that it occurs with SQLite.NET database too (so IdentityInsertString doesn't matter because it doesn't exist in SQLite).
An error occurs when many-to-one have "property-ref" clause.
My mappings are:
<class name="DomainModel.VirtualCardNumber,DomainModel" table="virtualcardnumbers" lazy="true" mutable="true">
<id name="Serno" access="property" column="serno" type="int" unsaved-value="0">
<generator class="native" />
</id>
<property type="HibernateDao.TString,HibernateDao" access="property" length="16" name="Number" column="number" />
<property type="HibernateDao.TString,HibernateDao" access="property" length="16" name="Vnumber" column="vnumber" />
<property type="HibernateDao.TString,HibernateDao" access="property" length="16" name="Mnumber" column="mnumber" />
<many-to-one name="Card" cascade="none" column="number" property-ref="Number" />

<class name="DomainModel.Card,DomainModel" table="cardx" lazy="true" mutable="true">
<id name="Serno" access="property" column="serno" type="int" unsaved-value="0">
<generator class="native" />
</id>
<property type="string" access="property" not-null="true" length="25" name="Number" column="number" />

Test program is:
VirtualCardNumber vcn = new VirtualCardNumber();
vcn.Mnumber="479084******9536";
vcn.Number="479084XXXXXX9536";
vcn.Vnumber = "479084P000001953";
vcn.Serno = 1;
vcn.Card = new Card();
vcn.Card.Serno = 1;
vcn.Card.Number = "479084XXXXXX9536";
session.Save(vcn);