Cannot change themes

I’ve searched high and low for a solution but I can’t seem to get any of the other built in themes to work. If I select Umbra for example, the Theme Options shows the new colors, etc. but the Calendar page will never change. I tried copying the files to wp-content/themes-ai1ec, still no go. Disabled my cache plugin, emptied all caches, etc.

What am I missing??

The page I need help with: [log in to see the link]