Clear cache not working. Why?

Okay so I’ve been trying to delete the so called cache. I have the WP super cache plugin installed but it’s not doing anything. At the top of the page in my site’s admin area, I have clicked on the “delete cache” so many times and it does nothing. Im running Firefox and have cleared it from there no problem but I can’t get it to be cleared from wordpress. Any ideas on what to do next?

Thanks in advance