Can't add new songs

[SillyDreamer]

When I try to install a new song I receive an error like this:

Installation of package failed!
Value cannot be null.
Parameter name: path1

at System.IO.Path.Combine(String path1, String path2)
at MLKHelperGUI2.Program.Main(String[] args)

What should I do now? Please help me!  :'(

[OpTicFlutter]

I have the same Error, is there something we can Download to fix this?

[Dex]

That might have something to do with admin rights. You could try to disable UAC, install the song and reenable it afterwards.

[FireSans]

I have the same problem! Do you have a solution now or does it still not work?
I don't really understand what is meant with "UAC".Can you tell me what that is too?
Please :(