NOTE: If you have installed two SIM cards in your phone, you need to specify which one you wish to use for mobile data connection first. Go to “Settings” > “SIM cards” > “Cellular data”, and choose the SIM card you want to use for the mobile data connection.
To enable mobile data:
1. Go to Settings > Under 'Wireless & networks' choose "Data usage":
2. Touch the tab showing the name of your SIM card:
(If your phone only has one SIM slot, your phone won't have this step. Simply continue to Step 3.)
3. And then touch the Mobile data switch to turn it on:
4. Once it is on, you will see 3G/H/H+ symbol on top of the network bars:
The data should now work on your phone without any issue.