Illegal screen or not?

[dave30]

A1 is defended by B1 in transition. A1 uses teammate A2 by dribbling close to him running B1 into A2. A2 is moving towards the basket, but has not set up yet. Is it an illegal screen?

A2 doesn't seem to know that A1 is coming that fast behind him so he has no intent of setting a screen, but A1 knows exactly what he is doing to free himself from B1. A1 successfully ran B1 into the back of A2.

Smart play by A1 or illegal screen on A2 ? A2 was moving when B1 ran into him. Coach wants illegal screen. I had a no-call. What do you think?