It looks like you have the right pins. The RAMPS 1.4 X-axis stepper uses pins:
A0 (=54) for Step
A1(=55) for Direction
38 for Enable
Does the motor not even hum?
Have you tried a slower step rate? At 60 microseconds per half cycle you are trying to go from 0 to 8333 steps per second instantly. If a MUCH slower rate (like 100,000 microseconds per half cycle: 5 steps per second) works then you should consider adding gradual acceleration to your step rate.