Can't launch link in application

My friend uses Sopcast to watch sporting events. The way it should work is you click a link in your browser that looks like this: sop://broker.sopcast.com:3912/12345 and the right channel should open up in the Sopcast software.
They use Windows 7 and IE 9, but it only works right for them from the administrator's account.
From a normal user's account clicking the link in IE 9 would open up the link in a new tab (as normal) and launch the Sopcast software, but would not tune it to the right channel.
Under the administrator's account it did initially require 2 or 3 permissions, but as the regular user it doesn't even ask.
I tried changing the regular user account to an administrator and reinstalling the software by the new admin, but it still did not work and did not even pop the permissions.
Only lowering the UAC all the way to 0 made it work, but upping it again even one notch disabled things again. It never asked for any permissions, like it did under the other account.

I searched and found others with somewhat similar issues, but no direct solution.
I guess Windows 7 blocks it for the regular user, but how can I authorize it? Make it ask me?
Should it have been working or is it something generally blocked, on purpose?

Thanks in advance for any help or comments!

Ideas anyone?