Post Variation Margin

Hi

I have a scenario for Commodity Futures. Thus I created a new product type 70D and opted for "Futures style" margin management

I have made the relevent configs for flow types,Transaction types and update types

Now when i create a purchase (long) transaction using Transaction type 400 and want to post variation margin on subsequent days using T code PMVM - i get the message - No flows exist.

I need help on how to post variation margin for commodity futures - am  i missing any step here?

I have read the SAP documentation and done the config ?

Please help out on this

thanks

swami