Originally Posted by Kuntry
Most likely it wont work yet because themes are still written for the old "SMS" app and not the new "Messages" app. There is a compatibility issue that may be as simple as redirecting the theme to correspond with the app title "Messages" instead of the app title "SMS"
Yes, you are right!
I use iphonebrowser to go into my iPhone, and change my theme's SMS icon's name to "Messages", then it replaced to theme's icon.
Unfortunately, I have no idea for SMS theme...