Astra life twinport key doesn't work?

I wonder if anyone have had this problem and can help please. Basically, I have an 06 Astra and when i bought it 1 of the keys didn't work remotely. I've changed battery, and tried to re-synchronize by truing the ignition in the 2nd position but still no luck, I even put a little peace of tissue and paper in between the battery, still no luck. Now, my other key still works fine and I am just worried if that stops working too, I can't manually lock the car through the key hole on the door as it seems to be only locking the driver door, any suggestions on any of the issues would be much appreciated... Also, I've read this other forums about sitting in the passenger seat locking through the dashboard, still no luck,,
thanks