I made a list of applications that don't enable me to mount ISO-files. Here:

PowerISO doesn't mount
Virtual CloneDrive doesn't mount
ISODisc doesn't mount
KernSafe doesn't mount
OSFMount doesn't mount
Pismo File doesn't mount
WinISO doens't mount
Daemon Tools doesn't mount

What should I do?

You can use Virtual CloneDrive by Elaborate Bytes. It is freeware. I used it for years on Windows 7. It allows you to mount an iso (actually several formats of images) as a drive.

If all the above fails it is possible that your .ISO files are corrupt. I did run into a client that had such troubles and it turns out all their .ISO files were from less than reputable places and not one were any good as they used a downloader app that was cracked (pirate) and broken.

I have another package that I would like to mount but the results are the same. So it's possible that both are corrupt. But I'm still hoping that there is something else that can fix the problem. Thanks for your comment anyway :)

@X. I read your last reply and you wrote "possible both are corrupt" so to me that tells me you are only testing with TWO ISO files? The likelyhood of these being bad just went up.

Can you share how I can test your ISO files? Where can I get them?