Phantom 2 wont fly higher than 20ft

I replaced 4 motors on my Phantom 2, then recalibrated accoring to this video.



When I start the motors and begin to fly up, I reach about 20ft and it wont fly any higher.

Also it seems to be jerky when hovering in one place.  The wind was not strong enough to cause the jerky flying.

It seems like something is wrong with the computer, because it makes the movement on its own.

It also starts to decend on its own.

I am stumped on what it happening.

Any suggestions??

When you say "computer", I think you mean your copter, correct?

Does it descend and then auto-land? I take it your TX batteries are full? All your batteries are fully charged? Are you getting any alerts or pop-ups in your display? What do you mean by "jerky flying"? Please elaborate a little on this. In fact, a little more details altogether would be great.

Cheers.

What motors did you use? And prop?

Are you near an airport, or have you messed with max. hight in Assistant ??

What do the LEDs on the Phantom show when you hit the 20 feet?