Hi @Xomax - welcome to the forum
Don't worry we're here to try and help. I've already fixed up the formatting of your posts to make them a little more readable.
Questions:
What file extension does the file have? It looks like it will be *.PDN - but I'll get you to confirm that is the only extension (and not something like MyFile.png.pdn)
Did you select the file type from the dropdown list in the Save dialog - or did you type it in manually?
Are you able to ZIP the file and upload it? If it is too big for the forum, upload it on Imgur or another file hosting site and paste the link here (assuming the image is family friendly).