Find this on skill.c
if( sc->data[SC_DANCING] && skill->get_inf2(ud->skill_id)&INF2_SONG_DANCE && sd )
skill->blockpc_start(sd,BD_ADAPTATION,3000);
Add comment line // on that line
It should be like this
//if( sc->data[SC_DANCING] && skill->get_inf2(ud->skill_id)&INF2_SONG_DANCE && sd )
//skill->blockpc_start(sd,BD_ADAPTATION,3000);
After editing it, recompile your server