I am trying to simply edit a Gnome theme that I have downloaded by changing a few values in gtkrc and re-taring/gziping it up.

I can succesfuly load the original theme by dragging the .tar.gz into the theme manager and selecting it from the Theme Details panel, but once I try to drag my edited version it returns "The file format is invalid".

The permissions/owners are exactly the same and I'm not sure what I'm doing wrong.

The command I'm using to zip it is:
tar -cvzf GTK2-My-theme.tar.gz ./theDirectory/
Any insight would be great,