Just downloaded the one from the first post of this thread, re-uploaded it to
http://random.menthix.net/Imitate_beta2.plsc maybe your download got corrupted somehow.
I am currently using Plus! 4.20 beta (which will be released to public in a few days), so it could also be just on your Plus! version. Maybe someone else can confirm that.
I'm currently using:
MP!L 4.20 beta3 (4.11.0.260)
WLM 8.1.0178.00