I cannot move a servo manually
Based on your question, your PWM may be way too high.  A typical hobby servo might need a signal at 50-60 Hz.  Let's take 50Hz as an example.  That means that every 0.020 second, it might need a pulse around 1.5ms (0.0015s) to seek "center" position.  So, that equates to about 7% duty cycle.  Try a lower PWM range to get pulses of 0.0010s to 0.0020s at 50Hz.

And as the comment suggests, the GND connections must be common.