Stacking Layers

Don’t know if I can explain what kind of problem I’ve got, which it bothers me for some time now and I just can not figure out why.

I’ve made my site with photoshop and all images are in *.*png, saved with transparency and in the same resolution 1000x750. I exported them into my working file in Flash. No problems here.

I’ve started to put each of the images in separate layers and in stacking order I wish, still no problems.
Now, I am about in 20th layers I am inserting the image, again in separate layer and what happened? The layer will cover over the layer which is almost at the bottom. Meaning…only the trasparency which is very strange.

Do you have any idea what could be the problem?