bitmap and colormaps

I have a grayscale raw image in a matrix (dimension 800x600) of unsigned char
(so every image pixel has range 0 - 255 ) .
I also have a graphic board ( VIRGE ) with 4 megabytes of RAM :
so , in windows95 screen properties, I can put (with screen resolution of 1024*768) max. 16777215 colors .
If , in screen properties, I put 256 colors : I can display, without
problems, my image using the API funcions: CreatePalette, SelectPalette , RealizePalette and then CreateBitmap and BitBlt ; but, if I put
in screen properties, of windows95, 16777215 colors, then, in this case,
my bitmap does not appear in the window.
I also saw , in the API, that the field palNumEntries , of LOGPALETTE structure (used by CreatePalette), is an integer 2 bytes length (so I can not put, in this field, a number bigger than 65535) .

I want that my bitmap appears also with number of colors (of windows95 screen properties) bigger than 256 colors .

How can I resolve this problem ?