Q:

Wp datetime format

I have an app that deals with time and it shows prayer times in 12hr format only ,it is very functioning without errors. 
one of my users sent me a message :
" app does not work in 24hr format,
when I changed my time setting from 24 hours to 12 hours it start work, actually here in shengun countries Nokia Lumia does not show 12 hours by default, to change the setting we would have to change region setting." 
I tried to reproduce the same error but I could not ,ofcourse I am not living in Europe. 
my question is what is different in Nokia Lumia in Europe from international version like in middle east from a programmer point of view ? 
So I can take in account in my app next update
thanks 

A:

my question is what is different in Nokia Lumia in Europe from international version like in middle east from a programmer point of view

Only one thing: the regional settings.  You can change them manually on your device or the emulator by going in the settings menu (in the region+language submenu). 
Unfortunately, "does not work" isn't precise enough to understand what's going on with your application.  A few leads though:

Having a time on 24 hours rather than 12 hours may change your computations
Parsing a decimal number or a date without explicitly setting a culture in the .Parse method can crash when executed in a foreign culture (by far the most common crash occurrence I've seen on Windows Phone)
The same way, converting a decimal or a date to a string without specifying a culture can yield different results depending on the country

