I just copied the DECAY.DEC (and evt.pdl) from /pgenerators/EvtGen/EvtGen/Private. The dspair.dec I took from topic https://forum.gsi.de/index.php?t=tree&th=4281&start=0& (this is very simple decay rules). Even if I run EvtGen (just from C code) specifying only DECAY.dec I got exactly same error.