wrong UOM in shopping cart with a contract as a supply source

Hi experts,

We are in SRM 7.0 classic scenario with ECC 6.0. SRM are creating SC with backend contract as source of supply.

1. We select a material from a catalog (MDM)  with UOM in material master with value "G"

2. In details /position in the SC, in  "supply of source" tag has a contract as a supply of source with UOM "ENV"

3. so the contract has different UOM of the material

4. The SC has taken the UOM from the material (material master ) instead of the contract.

The user cant change the supply of source and he cant change the UOM that is taken the SC

It´s behaviour not always is given. I mean that for some colleagues are determined correctly UOM in the SC and not others when we try to test the incident

Any suggestion?

Thanks in advance.

Best Regards,

Mar