Meljet-PSS merge problem (FS 2002)

Hi, a problem I have had several times in a row now (never before though): when landing my Meljet 744 with PSS panel, it jumps up and down on the runway!! My actual touchdown is picture perfect, perfectly stabilised on the LOC and GS already since 7 miles out, and my config is flaps 30, speed is as indicated/calculated by the FMS; I switch off ATHR once on the ground and then reverse thrust. Everything perfect, it's just after I touch down and reverse the engines that it starts jumping up and down.I have used one of the mergle files from this forum to merge the Meljet with the PSS panel.Could the reason be:- I use Autobrakes- retard too late- ATHR should remain switched on- weight (although I remained in the published MLW)What else? Something in the aircraft.cfg?Thanks