ranbud on "Plugin No Header Issue"

On one site (other sites have no issue) I am getting "The plugin does not have a valid header" no matter what plugin I try to install. It installs but when I try to activate it, I get that error. I have read many, many, many post on this and watched the video on zip in zip that can cause this, but that is not the case here. If anyone knows the answer or can point me to a topic that already explains it that I am not finding, I'd appreciate the help. Thanks
Using version 4.0