Using JBoss-3.0.0 with Oracle 8i

I'm trying to map a 1-n relation. All goes well with the jbosscmp-jdbc.xml file (the correct foreign key fields are created), but I cannot get it mapped to my entity bean.

In the UserBean (which has 1 Group)
public abstract Group getUsergroup() throws RemoteException;
public abstract void setUserGroup() throws RemoteException;

in the ejb-jar.xml:

<ejb-relation>
<ejb-relation-name>
UserBeanToGroupBean
</ejb-relation-name>
<ejb-relationship-role>
<ejb-relationship-role-name>
UserBelongsToGroup
</ejb-relationship-role-name>
Many
<relationship-role-source>
<ejb-name>UserBean</ejb-name>
</relationship-role-source>
<cmr-field>
<cmr-field-name>
usergroup
</cmr-field-name>
</cmr-field>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>
UsersInGroup
</ejb-relationship-role-name>
One
<relationship-role-source>
<ejb-name>GroupBean</ejb-name>
</relationship-role-source>
<cmr-field>
<cmr-field-name>users</cmr-field-name>
<cmr-field-type>
java.util.Collection
</cmr-field-type>
</cmr-field>
</ejb-relationship-role>
</ejb-relation>


The ERROR that I keep getting:

javax.ejb.EJBException: Method is not a known CMP field accessor, CMR field accessor, or ejbSelect method: methodName=setUsergroup;

Anyone?