[Chimera-users] how to play trajectory frames ?

i tried "open 3ft6.psf coordsets true coords 3ft6.xtc" but i get "*'coordsets' has no suffix*" error message. and with "open 3ft6.psf coords 3ft6.xtc coordsets true" i get "*Expected a keyword*". how do i play frames of a trajectory. i have the psf and xtc or dcd trajectory files available.