I can't upload any files

[InfiniteSpawn]

Right after I installed Tiny Portal (latest version), I tried to install a theme, but it when I tried to upload it, it says:

An Error Has Occurred!
The package you tried to upload either is not a valid package or has become corrupted.

I thought maybe it was just the theme I was trying to upload, so I tried to install another theme, but I got the same error. No matter what I try to upload after I installed Tiny Portal, it continues to give me this same error. Can anyone help me with this please?

~InfiniteSpawn

[G6Cad]

If you have done what i think you have done, you cant install a theme through the package manager, you have to install the themes through the theme manager
admin/themes and layout/

[InfiniteSpawn]

  Yea. I tried to do it with package manager. (Don't know what I was thinking)

Thanks for your help!