TransparentBlt return false in some printer devices.

I am using the function TransparentBlt of CImage class and in a lot of printers the bitmaps are printed in transparency correctly. But in some printer devices TransparentBlt function return false (for example Adobe PDF 6.0) and therefore the bitmaps are not printed. What can be the problem? How I can know if the printer will print correctly the bitmaps?

This is my code:

void DrawTranspBm(CDC * pDC, const CRect* pRt, COLORREF crColour, HBITMAP hBitmap)
{
CImage img;
img.Attach(hBitmap);
BOOL bRet=img.TransparentBlt(pDC->GetSafeHdc(),*pRt,crColour);
}

Can any help me please?
Thanks.

Yes, some printers don't have transparent ink nor do they have other means for simulating a transparent area.
Use BitBlt() instead of TransparentBlt() although the result might be somewhat different.

Thanks for the reply. If I use BitBlt also fail and if I use StretchBlt I don't get the result that I need. How can I know before to print some document If the printer that I am using can use correctly TransparentBlt function or not? I am comparing two printer devices (one printer devices print transparent bitmaps correctly and the other no) using GetDeviceCaps function I only see differences in this parameters (The results of GetDeviceCaps with the others parameters are the same in the two printers):

Printer ok Printer fail
LOGPIXELSX 600 1200
LOGPIXELSY 600 1200
ASPECTX 600 1200
ASPECTY 600 1200
ASPECTXY 846 1696
HORZRES 4958 9917
VERTZRES 7016 14031

Can any help me please? Thanks.

Even SHADEBLENDCAPS is the same in both?

Thanks for the reply.

Yes, in both printers are 0.

Can any help me please?
Thanks.