Syntax error in FM but activation happens

Hello,

I made an implicit enhancement to an FM. The variable i declared at the beginning of the enhancement is not visible to the FM. When i do a syntax check it throws an error saying "The variable XYZ is unknown. It is neither in one of the specified tables nor defined by DATA statement." But surprisingly the code activates. Can someone please explain the reason for this strange behavior ?

Thanks,

Jayant.