Biped append animation


My goal is to append biped animation at the end of the existing animation.
I couldn’t find an option to offset for the biped.loadBipFile, so I decided to use mixer, but the following code does nothing:

biped_node = $
biped_com = biped.getNode biped_node 13
biped_mixer = biped_com.controller.mixer
mixer_track_group = getTrackgroup biped_mixer 1
mixer_track = getTrack mixer_track_group 1
mixer_clip = getClip mixer_track 1
loadFile mixer_clip #singleClip @"D:\MehdiZangeneh\Temp\Walk.bip" false

getClip mixer_track 1 return false.