Originally Posted by santod (Post 1379111)

Ok, so you are running 6.5 Right? If so, good. After looking at that theme, here are some things you should consider, before and during install.
With Titanium disabled, you should completely uninstall the theme before following these steps.

1. Make sure you’ve got SDK Certs installed First (attached at the bottom of this post), install it, then soft-reset and continue to the next step!
2. Go to Start > Settings > Today > Items , and disable the “Windows Default” checkbox
3. Copy the theme .cab to your device and run it, make sure you install it in your device and not the storage card and soft reset.
4. Go to Start > Settings > Today > Items, and enable the “Windows Default” checkbox, also select Crimson Darkness (based on your device resolution) from the list of today themes and apply.
5. Enjoy!

Download

Hope that helps!