How to activate Product Classification

Helo all,

we are using SAP TM 92 and we want to activate the classification to maintain characteristics for the product. In customizing we have maintained under topic Classes -> Maintain Object Types and Class Types for table "/SAPAPO/MATKEY" a new object 300 (/SAPAPO/MATKEY). (which is nearly a copy from SAP ECC system).

What have I to do, so that I can maintain classification  data in product master data. When I press the button "Classes" in transaction "/SAPAPO/MAT1" i'm getting the message "No allocations found".

Thanks in advance and best regards

Georg