Batch Management - Changing Material level to Plant level

Hi friends,

We are configuring batch management for ECC 6.0 with CRM 5 .

I can see the batch level in my system as Material level. But we would like to convert batch level in to Plant level. when i try to convert the batch level i am getting error "This type of conversion is not implemented".

There is no batch record exists in the stock.

Please clarify why can't able to change to plant level from material level.

Thanks