AIR warning message in Auto mode

In checking some FMC functions out, to save time I loaded the MD-11 in the default engines running on the runway situation. Everything was as expected except the AIR panel was showing bleeds and packs off. I had to select manual to allow me to activate the system. I tried reselecting auto but the AIR system shutdown again. I took off in manual and eventually was able to revert to auto operation.The only difference I can see was from what I had done on other flights was that I had not used the APU to supply the pneumatics first, just going straight into an engines running situation.Only a very minor irritation really. ;)Incidentally in my rush I found I had too much fuel so decided to try the fuel dump system. Pleasantly surprised by the external view of my simulated polution!Kevin