Plugin installation – can’t create temporary files

Hi there,

Trying to install plug-in but get this message saying it can’t
create temporary file

Downloading install package from https://downloads.www.ads-software.com/plugin/wp-e-commerce.3.7.4.zip.

Download failed. Could not create Temporary file

Now I’m also trying to do it straight with FTP, the file
shows in my directory but not showing up in my plug-ins.

Anyone know what may be happening here?

thanks