I am trying to send an orbital lab (pretty heavy lab actually) to the orbit of Dres. I chosen to do this in two flights - one to send the lab itself into a high Kerbin orbit, second to bring it's propulsion system to the heavens. After a successful docking I've discovered that vessel's delta-V values provided by "Delta-V Stats" tool of MechJeb's are negative (so are vehicle's Thrust-to-Weight ratio values), yet the vehicle accelerates when blowing the engines. Is it some kind of MechJeb's bug? Or are those values real and I can only dream of sending this vessel beyond Kerbin orbit?