A couple other possibilities. I get the
actuator error thing all the time for a couple reasons. Basically that means that the receiver isn't receiving any pulses from the actuator. It can mean that the dish isn't moving, because it's frozen like Rainman said, however it can also be because the sensor wiring isn't correct. There are usually 3 wires, however with most actuators, only 2 are used, and if you use the wrong ones, it won't work. Also, if moisture gets into around where the magnetic reed switch is, sometimes the pulses are shorted out or damped a bit. Every time we get a heavy misty rain, I end up getting actuator errors on my dish, and everything is fine after it dries out.
Also, on some actuators, the magnetic wheel can be positioned closer or further from the reed switch, in the event that it isn't switching.
I'd recommend getting a ohm-meter, and hooking your actuator up to a car battery, and run it from the battery, while watching the ohm-meter across the sensor wires. If the motor turns, and the ohm-meter indicates alternating open/closed pulses, then everything is OK at the actuator, and the problem is either in the wiring or the receiver setup.
One other thing, is that about half the time, when I've hooked up actuators, I've hooked up the big power wires backward. If your actuator is fully retracted, or fully extended, ie at a mechanical limit, and you try making it go the other way, it will try going the wrong way, but can't, because it's at it's limit. Try manually moving the dish both ways, just to make sure it isn't going in the wrong direction.