Selected theme doesn't change anything

Hi

I have posted a related question before, which has been resolved.
However I don't know how you managed to re install a template.
http://stackideas.com/forums/zip-file-is-empty
However easy social theme seems causing another problem.

I have purchased a template sosyal from optimumtheme.
I was advised to ask you guys about the issue after I had "Invalid File Type" when I tried to install a specific zip via easysocial > Themes > Install
You can see the comment from their support.

http://www.optimumtheme.com/support/forum/easysocial_v1-3_theme-zip-invalid-file-type.html

Currently there seems another problem with EasySocial. For example even if I change the default theme between core themes of the component, nothing changes. For example if you set Dark theme as default, nothing changes on the front-end.

I have added my site info.

Many thanks