The gerrr on the servos means (at least from playing with my own servos!) your pulse is to long/short.
At least for my servos a pulse of about 1500 micros should center the servo, a pulse of about 1000 will send as far as possible on way and a pulse about 2000 will send it all the to the other exstream. The exact numbers seam to depend on the servo. There is no standard.
It would help if you posted/reposted your current code with a discription of your current problems.
Mark