bitblt

i use bitblt function to draw on a picture that is not visible and when i finished to paint that picture,with bitblt i paint to the picture visible,so i haven't got flickering problem.
but when i do this three or four times,it does wrong and it paint nothing.
why does it happen?
thank you isabella

im not sure what could be wrong without code, could you post your project?

im not sure what could be wrong without code, could you post your project?
ok

ok
i solved my problem,i change the function transparentblt,i use api function instead of my function and all goes right