I'm not quite sure what you're trying to do with this system, but I think it would be easier just to call a level up. If you use the level up event command, it will also increase the current class level by one. As far as I can see, your code SHOULD be working. The script call command acts a bits screwy though, so play around with it (where each line break is) a bit, that might fix the problem.
BTW, glad you're using my system ^_~