chroma key with surface object

Hi everyone,

I am playing with surface object and i would like load a JPG image and use a color (with a Little threshold) to get a chroma key... i mean, i want to use a group of colors like as transparent color.

I have tried to créate a alpha channel (i have never got it), I have tried to assign transparent color... but nothing

How can i do it?

thanks!

I have already solved the problem... a problem in my code...

thanks