Flex Accounting For Procurement

Hello,

We are trying to create flex accounting using DMAAI 4320, Company, Document Type, on Subledger, and subledger type "O"  for the file F4301 and using Data item DOCO.

we modified the processing option on P4312 and set the Flex to "1" as active; and then we did the following test:

1- create a purchase order

2- Purchase Receipt

3- went to P0411

4- Checked the OV

5- but found that no Sub-ledger was written

Is there anything which need to be taking care into consideration  while doing the above setup? Or is it that the sub-ledger type "O" doesn't work with F4301?