Hi Anbar
Normally (for me) it works with any power source unless it’s below 1A, and yes you should try another cable. One more thing is that there has been reports where people had issues relating to the A rating on the power source. While this seems odd to me (it’s current draw, so as long as the power source can deliver enough amperage it should work), some reported only 1A and 1,5A worked, so perhaps it could also be this? Have a look at this thread:
Do you mean that there is no signal in the camera app or that the UR12 is not selectable? If there is no signal, turn on phantom power. If the Ur12 isn’t recognized it’s probably an updated ios thing, but as i don’t have a camera connector kit for my iPad i can’t test that.