Flash cs 5

i started my project on Flash CS3 now i opened my project on flash CS5 and when i compile the project it shows the following error .

TypeError: Error #1034: Type Coercion failed: cannot convert flash.display::MovieClip@298c8a61 to fl.controls.TextArea.
at flash.display::Sprite/constructChildren()
at flash.display::Sprite()
at flash.display::MovieClip()

Can anyone tell me wht is the problem,
please help me out.