I created some mat files for poser pro pack and needed to created some customised mat image files so I loaded the PNG file in photoshop and edited it by adding a render image to it and saved it back as a png file, but when back in poser pro the image dosent show up anymore and the window on the pose library is Blank. The file itself works by setting the materials but no image shows up on window. Can anyone help me resolve this?

So many things that can go wrong, so little time .... Alpha channel. You need an alpha channel in your resaved .png. If Poser can't find an alpha channel, it assumes by default that the entire thumbnail is completely transparent. I learned this the hard way (trial and error). Of course, you might be having a different problem altogether.

But how do u create an alpha channel Little dragon?

It's ok, figured out how to do everything now...Render image in poser, then export as a png, import into photoshop and item is rendered on a transparent background...Edit it then resave as a png in mat pose dir and poser pro dispays it as normal on neutral background....Yippee!..Phew!

Glad you got it fixed. I could tell you how to create and work with alpha channels in Paint Shop Pro, but I don't have Photoshop, so couldn't walk you through that software's process.