I get the following error: An error has occurred:
2 - move_uploaded_file(/home/pretogra/public_html/layout//chameleon/styles/logo/logo.png) [function.move-uploaded-file]: failed to open stream: Permission denied @ /home/pretogra/public_html/admin/plugins/chameleon/index.php line 275

Any ideas?

This is a permission issue. The web server cannot write to the following directory:

/home/pretogra/public_html/layout//chameleon/styles/logo/

You need to change the permissions to ensure the web server can write to that directory and then the logo should upload without any problems.

Thanks!
mark