quite a few flash error messages are unclear but error 21 means exactly what it says, you have functions with the same name. for example,
are both overF() function names. how would a computer program know which one should execute?
fix that by using different function names for different functions. if you only need one function named overF(), don't write it more than once.
because you're using overF() and outF() somewhere else. use movie explorer to check.