Canvas mode script bugs??

I am coming across bugs. I am not able to identify what is happening. I will have some basic script written that is working well. I add some code for a new vaariable to a dynamic text field or transforming a movie clip. It may have a script error and after correcting the script error - it still doesn't work. Like maybe ghost characters or something. The corrected script doesn't have errors, but it will not work anymore.