I have an alpine iva w205 head unit, but need to take it out to attach the gps antenna so that it will function with my docked blackbird navigation unit. I have the keys and put them in the slots on either side of the unit, but it won't budge. The manual says it should slide out, but it doesn't seem to be going anywhere, and i am afraid of pulling to hard in that i might mess up the motorized face plate. What's the deal?