Imageready disposal method?

Aren't transparent sections supposed to show background?

[Clark]

I've always had the same problem creating small moving gifs. I create a background and say "no disposal" method. Then on the following frames I create a small image where the rest of it is transparent. Going with the assumption that the background will show through. But of course it doesn't. I'm really confused. What's the trick?

[Ingolemo]

At a guess, I'd say that you want disposal to be on if you don't want previous frames of the image to show through.

[Clark]

I do want them to show through but no matter which of the 3 I set it to, the transparent part of the new frame seems to overwrite the previous frame. I must not be understand how it works?

[Clark]

Does "Lock Transparent Pixels" have anything to do with it by any chance?

[Clark]

Sorry for the serial posts but another question. If you have a .psd file, can you convert a layer that is jpeg into a gif?