Acct assignemnt for the PR Third Party sales scenario

Hello,

In third party sales, when we create a SO it automatically creates a Purchase requisition. It is a Account assigned Pr with acct assgt cat as "X".

For this acct assgt cat "X" I have VAX as the acct modifier.

In OBYC i have set the G/L for this GBB - VAX

The PR that is getting generated from Sales order is not taking this G/L instead it is picking the G/L assigned from BSX trasaction key.

My question is in a Third party scenario it shud pick the COGS G/L that we have assigned in VAX or the stock G/L assigned in BSX ??

If it shud be the VAX G/L what could have gone wrong?

Please advice,

Thanks a ton in advance.