Cannot create property background_mc on mysqlurl

there are 3 classes in my library with base class movie clip
menucaller
mysqlurl
background_mc
menucaller and mysqlurl each have an .as file associated with them
background_mc is just a white square in mysqlurl
all 3 are exported for actionscript
on the stage i have instances of of menucaller
on mouse over of menucaller, menucaller summons mysqlurl via the .as file
when i publish as .swf and navigate to the frame where there are instances of menucaller, the menucallers appear just fine
but i get the error

ReferenceError: Error #1056: Cannot create property background_mc on mysqlurl.
at flash.display::Sprite/constructChildren()
at flash.display::Sprite()
at flash.display::MovieClip()
at mysqlurl()
at menucaller()
at flash.display::MovieClip/gotoAndPlay()
at TEST1_fla::MainTimeline/PALclickHandler()

i fixed this once before by just copying and pasting all of the layers into a new project, but its not working anymore
please help me this error is boggling my brain
thank you very much for your help in the past and i hope you can help me figure out this one, its the last thing to finish a huge project