Help with mapping set - Hibernate

I'm having problems writing a part of a mapping. First of all, I have these mappings:

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 
 <hibernate-mapping>
    <class name="auge.bean.MpProducao" table="MPPRODUCAO" >
        <composite-id>
            <key-many-to-one name="materia" column="materia" class="auge.bean.MateriaPrima"
                    lazy="false"/>       
            <key-property name="numeroOrdemItens" column="numeroOrdemItens" type="java.lang.Integer"/>
        </composite-id>         
        <property name="quantidade" column="quantidade" type="java.lang.Float" />
        <property name="baixaDada" column="baixaDada" type="java.lang.Integer" />
       
       <many-to-one name="cor" column="cor" class="auge.bean.Cor"
                    not-null="false" lazy="false"/>   
                   
    </class>   
 </hibernate-mapping>

[code]
  <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
 
 <hibernate-mapping>
    <class name="auge.bean.OrdemItens" table="ORDEMITENS" >
       <id name="numeroOrdemItens" column="numeroOrdemItens" type="java.lang.Integer">
           <generator class="assigned"/>
       </id>           
       <property name="tamanho" column="tamanho" type="java.lang.String" />
       <property name="qtdePedida" column="qtdePedida" type="java.lang.Integer" />                           
       <property name="qtdeFabricar" column="qtdeFabricar" type="java.lang.Integer" />
       <property name="processoAtivo" column="processoAtivo" type="java.lang.Integer" />       
       
       <many-to-one name="ordemDeProducao" column="numeroOrdem" class="auge.bean.OrdemDeProducao"
                    not-null="false" lazy="false"/>       
                   
       <many-to-one name="produto" column="produto" class="auge.bean.Produto"
                    not-null="false" lazy="false"/>       
 
       <many-to-one name="cor" column="cor" class="auge.bean.Cor"
                    not-null="false" lazy="false"/>       
    </class>
 </hibernate-mapping>

I'm trying to put into the second mapping (auge.bean.OrdemItens) a set of the first one. I've tried it this way:

But I get an error saying: Foreign key (FKC24B75B6576D388F:MPPRODUCAO [numeroOrdemItens,materia])) must have same number of columns as the referenced primary key (ORDEMITENS [numeroOrdemItens])

What's wrong? Thanks for the help