jefkar, you said, "checked the fluid level and it is good." In many systems the reservoir must be full to the overflow plug or it might read as "low" which would trigger a jack down error even when the jacks are all up. If the fluid level is as described, then I agree with those that suggest the sensor or the wiring to the sensor is bad.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI