Problem with 'TypeError'

Hi all

I’m getting an error:

TypeError: Error #1010: A term is undefined and has no properties.
at Main/initGame()
at MethodInfo-7()

Here are my source files:

I’m also looking for a simple way to show my ‘enemies’ on random base on my platform screen. I already made an array with the x and y coordinates but I don’t know how to make AS3 print them on a random way on the platform windows.

Please take a look, hopefully someone can help me.