Problem with Counters

Hi,

We have created two Usage items, USG1 and USG2. USG1 and USG2 have different price breaks defined. They are under the same counter group CTR_GRP1 with association type as Item and Item Names assigned to the same. 

For star item D*XYZ123 we have shipped 10 units which are serial controlled and having different serial numbers. 

When creating a contract with a Usage line and selecting usage USG1 I am not seeing the serial number, ideally USG1 and USG2 need to be entered for the same serial number under the same contract because I give two seperate usage based service to the customer.