Validation to stop manual posting to GLs through f-02

Dear Gurus,

Our Client has the followign requirement where we need to stop manual posting to a Few COGS, hence If I check "post automatically" only , it is also not allowing us to do MIRO, Hence I am creating a Validation rule to stop posting manually.

I created a set with the GLS and gave the following at the line item level in GGB0

Prereq:

SYST-TCODE = 'F-02'

Check:

BSEG-BUKRS = '1000' OR BSEG-BUKRS = '1100' AND

BSEG-SAKNR IN COGS, where COGS is the set, However it is not working.

Please help.