Neither Slide-In Nor Pop-UpWorking

I have made an attempt to use both plugins with no success.

They were just installed tonight, so completely up to date.

I believe it is an issue with the header / footer call.

If I edit these, will the theme break?

I am using the Creativo theme and have not had any other issues untl now, but although recommended by WPMU, it is not a theme of the network.