Why my 3G/LTE didn't Turn On?

I have a problem with my iPhone 5, right now each time I try to Turn On 3G or LTE my signal status always displayed as E (edge)

I was try to speed test and this device running on slowly network connections on E.

I was turn off and turn on on Settings > Cellular> 3G

Any clue how to fix this issues?

I was run on iOS 8.4