I start up my Phantom Vision 2+ and when I look at my phone, it says, Calibrate Transmitter Required (w/ a little MC logo behind it) and so I calibrate it using this guide (http://wiki.dji.com/en/index.php/Phantom-Transmitter_Calibration) and no matter what I do, it always says Calibrate Transmitter Required and it will never take off. I have calibrated the compass, like I do everytime I fly it.
I know it probably is a simple error and I am forgetting one small thing, but I can't think of what it is.

Maybe you should try running the transmitter calibration in the PT2 assistant.
That way you are calibrating the transmitter to the Phantom and not just calibrating the sticks as you are using the link you supplied.
Worth a try at least.

That did it Thanks!
The only problem I noticed is that the Quad spun on its axis as it descended from higher altitudes (200-300 ft) but when it got below that it acted normally. Probably some weird winds up there in the sky.