Plugins cannot find the required folder

I have asked this before, over the last ten days. Somehow either I posted the question in wrong forum, or if as attached to previous problem, lost.

Be that as it may? Now I can use dashboard, but it cannot load plugins. Each time I try the same error message. Could not create directory. /home/username/public_html/wp-content/plugins/wp-e-commerce/ All other plugin attempts create the same message, yet looking at my file manager I can find the folder. In fact I can find 2 folders. One within a folder marked wordpress 2.

I would appreciate some guidance on this issue, please. Thanks!