well since i posted this in the CRV forum no one has even looked at it and i leave soon from work so i won't be able to check it untill later tonight. anyone know how to fix this?

My dad, being the thoughtful husband he is, lost my moms gas cap. The emissions light came on after liuke 20 miles and they replaced the cap with one from wal-mart (supposed to be an oem replica) well the owners manual for the CRV says that after one trip the light would go off but it's still on. anyone know what the hell to do?