No expert, but I think your problem is in the servo drive timing. A standard RC servo requires a pulse between 1ms and 2ms (1.5ms represents centre stick) repeated every 20ms. It looks like you are simply sending a value of 50 or 100 which is on the limits or outside its range, and you are not repeating this within the 20ms time frame.
There are plenty of examples on the forum for servo drivers, have a go at getting your hardware working with one of those and then use that as the driver for your project.
Here are some examples:
http://www.rentron.com/servo.htm
http://www.rentron.com/SerialServo.htm
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