A 2004 Jayco motorhome is required to undergo an emissions test when obtaining California registration.
The smog technician needs to enter the vehicle's year, make, body type (smog tech needs to enter "motorhome"), model, number of cylinders, engine size, and for motorhomes specifically, the motorhome's engine make and engine year. This is where the differentiation is made between standard automobile and RV.
Furthermore... the inspection must be conducted on a BAR-97 smog machine (used for vehicle's which weight over 14,500 GVWR), as opposed to the new DAD machine, which can only smog check 2000 & newer model vehicles under 14,500 GVWR.
If the smog technician utilized the DAD machine to inspect your Jayco Greyhawk motor home, the system would not allow him/her to proceed with the inspection. We can not be certain that this is what happened however it is a possibility.
Your best alternative in this matter is to have another smog station attempt to smog check your RV. If that also fails, contact the California Smog Check Referee's Office at (800) 622-7733 for information on how to proceed.