[HECnet] RSX SYSGEN problem

I can t figure this one out I load RSX11M+ from tapes and do a SYSGEN. All goes perfectly. But then if I do a SYSGEN again (say, because I want to change something in the first configuration) several drivers fail to link. Looking at the map file for one, say DLDRV, shows Undefined references: $BLKC2 $BMSET $CVLBN $MPUBM $RLCN $RQCND $STMAP $VOLVD They look like system service calls to me, but the second SYSGEN was done with the same executive options as the first. In fact, I used the saved answer file for that part of the SYSGEN all I did the second time around was to change the peripheral configuration part. Is there something I m supposed to do to clean up or re-initialize after the first sysgen? Thanks, Bob