MultiWii

I have successfully connected my fs-i6 RC transmitter to my flight control, which contains Arduino nano and MPU6050.
And when I push the sticks, the numbers on MultiWii GUI do respond, but the motors won't!!!!
Then I checked the output of the pins that send PWM signal to ESCs, they are PWM signals, but the duty cycle never changes no matter how I push the sticks.
There must be something wrong with the configuration I believe.
I just don't know where it is. If this gets solved, the drone can take off in a second. Please help me, thank you all.

Have you connected to the right pins ,its 3,9,10,11 and select board nanowii in config.h when you open in arduino ide.
And are you arming the copter ,its done by throttle=min and yaw = max on your transmitter only then motors will respond. You can also set arm via Aux in the GUI.And there's a parameter in config.h to arm only when flat ,if you have uncommented that then keep the rotor flat and then try arming.