Image optimum size for epub2

I frequently do epubs but a few days ago i detected a problem I'm trying to resolve and couldn't yet.

Some pictures, it happened with cove pictures or others inside the books, doesn't show in ADE for Android when i change the size of it. At the desktop I don't have the problem. 

All images are in RGB, 8 Bits, sizes multiple of 4.

I try to make the cover 1728 x 2500 px.

First i thought it was a problem of the propotions that where not multiple of 4 but then i changed that it continues to not show the image in ADE for androd.

Does anyone knows something about it?