OS and Theme help needed!

i'm so confused :(

some themes work.. some themes don't! and i was thinking it was due to my phone but i got it replaced so now it's a brand new phone and i'm still having the same issues!!

i am on os 5.0.0.681, so when it says to click OTA for 5.0 on a theme, i do and it doesn't work properly (active/incoming call screen doesn't show the themes just the default BB blue) i have even paid for one recently and same thing!

ITS REALLY BUGGING ME. is it because i am from the UK on Orange and am downloading from american sites? or is it because some of the themes are designed for os 5.0.0.822? i always reboot/set permissions to allow but no luck.

having same issues.. . . i've had to give up downloading some themes because they don't appear at all! D: