Shopp Plugin Image Upload Error

I keep getting the following error message when trying to upload images to the category section or a product section.

An unknown error occurred. The upload could not be saved.

After a complete new database and wordpress install and upload of the plugin I have this trying to work with no other plugins installed and on the default theme.

I really need some help or advice on how to correct this error as otherwise I cannot use the Shopp plugin.

Please help!!!

Many Thanks