I don't think there's a bug
per se... It sounds like mistakes were made in copying the hack code to the newer files. (Leaving out the opening { bracket would do it.)
If you could post the specific error message PHP is giving you, I can help you out.
EDIT: Just to clarify things, all you're doing with this hack is replacing the standard vbdate() function with the new hacked version. And you're adding the vbdatenoty() function. The line numbers change with every version, but the process is essentially the same.