HI,
Go to tcode OBY6 and double check whether the CoA is mentioned for the respective Company code.
Also check in tcode ob62 , what other company codes are assigned to this CoA. If both are correct, then check in FS03 any GL account putting your company code. If system says, GL account is not created in Company code zzzz, then by tcod FS15 copy all Gl accounts from another company code ( with same CoA) to your company code.
Cheers,