backbuffers and transparency

for some reason blitting to the back buffer won't allow me transparency. if i do a direct blit to the form1.hdc there is a flicker but the image has transparent parts(with a mask), but if i blit to the back buffer:

BitBlt hdcBuffer, 0, 0, wid, hgt, hdcMask, 0, 0, vbSrcAnd
BitBlt hdcBuffer, 0, 0, wid, hgt, hdcBitmap, 0, 0, vbSrcPaint

and then to the form1.hdc:

BitBlt Form1.hdc, 0, 0, wid, hgt, hdcBuffer, 0, 0, vbSrcCopy

the background shows up. any ideas on how to correct this?