Why my Micromax canvas doodle 4 not detecting all Bluetooth devices?

[AC Question]

As mentioned, I have a Micromax q391 running android 5.0 lollipop. I have been trying to run an app for Nike+ Fuelband. the app run fine but report that cannot detect my device via Bluetooth. I checked on BT on the device & on the phone but the after searching for while cannot detect. I have tried a few of my friend's phone and the can detect. My question is, it the problem with Bluetooth or the phone?