Remote key problem

My car's remote key does not unlock/lock doors and open trunk. It doesn't even make a clicking sound to show that it's trying to open them.
What could be the problem?

The chip inside the key came with the car so I am sure it's the one for the car. I have already replaced the battery so the issue is not a low battery. The red light on the key blinks when I press the above buttons which probably means the key is sending out a signal.
Somebody please help.