When is a CGBitmapContext not a BitmapContext?

Question

I have a CGContext that I create with CreateARGBBitmapContext from here. When I do CGBitmapContextGetBitsPerComponent it tells me 8 bits per component (Which is correct) However, when I do CGBitmapContextGetBitmapInfo or CGBitmapContextGetData, I get NULL. Those are only supposed to give NULL when the context isn't a bitmap context. However, CGBitmapContextGetBitsPerComponent should give 0 if it isn't a bitmap context.

any ideas?

Edit: I should be able to draw a B&W 1bit CGImage into an RGB Context, right?