If the Controller and Drive are separate units, make sure the DRFLVL is set correctly. Also make sure that the drive is enabled with the DRIVE command. If they are in the same unit (APEX615n and ZETA61XX units), then the DRFLVL command is invalid.
Servos: make sure that the Enable (ENBL) pin is grounded.
Steppers: make sure that the P-CUT pin is grounded.
Type the command TASF. This command provides good information about the status of the controller.
Are either bits 17 or 18 on TAS high?
YES: A hard limit is hit.
Are Hard Limits being used?
YES: Check to see if the load is at a limit; if it is not, then check to make sure the wiring is correct.
NO: Disable the Hard Limits with the LH command.