Invisible bitmap when used in Delphi

I have been developing some ActiveX controls for the past few months and one of users using them has a small problem with some of the controls. When the controls are used in their Delphi environment, the small (16x16) bitmaps are gray instead of full color. Not all of the controls are doing this, just a few. The strange thing is that the same macro is used in all of the controls to display the bitmap, but some work for them and some do not. In VC++ I have no problems at all.