Can't TAKE OFF!

[youtube]https://www.youtube.com/watch?v=Yoioa_gFiHU[/youtube]
[youtube]https://www.youtube.com/watch?v=6ujX9bJ0Oeg[/youtube]

I am new to APM, after i install all my stuff on my quad,unfortunately, i can’t take off on my first flight.
It seems that one of the motor didn’t have enough power to lift up the quad(I slow down the video and find out the motor had a different speed).I have already checked all the motors spinning direction and propellers were installed right, but it just doesn’t work. Can someone check out whats wrong with it? Thanks you. If you need more information, please tell me.

Sunnysky v2216 KV900
Sunnysky 40A ESC
3s Lipo Battery 5400mah
APM2.6
Devo 10 with rx1002

btw, sorry for my english grammar.

Hi ,

Okay , you checked props mount , Motors in the right output port ? APM in right flight direction ?
Compass and accel are calibrated ok ?!? ESCs are calibrated ?

So my test would be the folowing : Put your copter in flight direction and stand behind it.
arm the copter -rise throttle up to 40%
now try gently the rol and pitch and check if the copter is lifting right .
means : stick up -> copter lifts its back
stick down -> copter lifts its nose
stick right - copter lifts left side
left - other way round
Put it on a slippery ground (not grass) perhaps inside plain floor - try the yaw left and right.
If all this is okay your copter should fly …
greez
acdc