Having some trouble with force-carbing

This is my first time force-carbing. I first injected the corny with 30 psi and shook it around for awhile, then I left it for a day or two and then let out the pressure, then set it at about 12 psi at 40 degrees. I have about 6 feet of line from the keg and it's all inside the fridge including the co2. It has been coming out way too fast and even when I turn off the pressure to have it come out it is still pretty flat. So I left it at 12 psi for a couple weeks and it is still the same way. What should I do?

 

+1 on overcarbed. Ive never really cared for the "shake and bake" method. If you have the patience your much better off setting your reg to the correct pressure and letting it sit for a week or so. This will tell you about were your reg should be set. http://www.kegerators.com/carbonation-table.php

 

This comment is based purely on what I've read (I have yet to keg a batch), but have you tried a longer tap line?