fitit on "You do not appear to have any plugins available at this time."

Hi,

"You do not appear to have any plugins available at this time." Is the message in my Admin/Plugins despite having Akismet installed previously.

Anyway, I've used the "Add New" in the Admin/Plugins area and selected something like JetPak and despite saying success, etc when I "activate" I get this error, "The plugin does not have a valid header" in Firefox browser.

Note: This issue was opened a few months ago in another post and never resolved.

Note 2: I've tried uploading FTP and they do not show up in the Admin/Plugins area.

It is a standalone installation of the latest version of Wordpress on Apache/CentOS.

Please help.

Thanks