How to show file format icon in the corner of thumbs

Hi,
I have bought Codec Pack and it's super! But I would like to ask you two questions:
1) I would like to know how to show file format icon in the right bottom corner of the thumbnail. Respectively, I can see this by PDF, INDD and AI file but there is on icon at PSD files. How can I make it works?
2) This question is about PDF thumbnails, I can see some PDF thumbnails and some not. I don't know why, what should I do?
Thanks, Vitezslav Outly
I have bought Codec Pack and it's super! But I would like to ask you two questions:
1) I would like to know how to show file format icon in the right bottom corner of the thumbnail. Respectively, I can see this by PDF, INDD and AI file but there is on icon at PSD files. How can I make it works?
2) This question is about PDF thumbnails, I can see some PDF thumbnails and some not. I don't know why, what should I do?
Thanks, Vitezslav Outly