One of the very reasons I am glad I did not use Game maker.
Yeah, you just used another dumbed-down programming language. Its nothing to do with Game Maker, shows your knowledge on the subject just fine.
The bug is to do with two things. The first is there was messy DLL reading and loading, which is being reworked in AB 2.0. You also need to allow AfterBlock to read AND write to the folder, so if you have any computer settings preventing this it ain't gonna work.