Stucked flow

Hello to all good people, after some time I have again one trouble with PM.

U have a conveyor where I need to transport parts from one place to another, parts are from assembly. Unfortunatelly it works only for the first pair of assembly parts, then it stops.

Attached is vcmx file where you can see it.
Transport.vcmx (1.3 MB)

Have you got any advice what I’m doing wrong?
Thank you in advance for your answer.