ChoosePixelFormat() & MDI

i had originally written an opengl program as a SDI, but have to change it to a MDI w/ only a single child window that needs to render opengl…it worked fine before changing to MDI, but now it always returns 0 when i call ChoosePixelFormat() and returns the error 126 -“The specified module could not be found”
any help would be greatly appreciated…thanx