transparancy problem

Till now I made clothes in photoshop on a transparant layer and saving to SL as a targa.
What should be transparant is transparant.

But I seem to have changed some setting because when I upload textures now the transparant part is white

I also see them in my photoshop previewer as white

I dont have any idea what I did wrong and how to change this...

Does anybody has an idea?

Thanks a lot!

I read the alpha channel guide and solved my problem. thx