Hi Sanjai,
Define validation as shown below:
Prerequisite
SYST-UNAME <> 'USB2'
Check
BSEG-HKONT = '999000' OR BSEG-HKONT = '999001'
Message
Message Type "E"
Message Number "007"
After create it, you have to activate for both the co.codes in OB28.
Regards,
Mukthar