ASA Illegal Substitution Question

[BretMan]

Having just received my ASA certification, this was a little new to me when it was covered in last weeks local rules meeting. Thought maybe some of the experienced guys could clear this up.

If a coach attempts to make an illegal substitution, should the umpire:

- accept the sub without comment, and wait for the other team to appeal before enforcing the penalty, or;

- inform the coach that the sub is illegal and prevent him from making it?

From what I got in class, the instructor seemed to be telling us that you allow the sub, then wait for the other team to appeal. He did suggest first asking the coach, "Are you sure you want to do that?" before accepting the change, thus giving the coach a chance to double-check his sub and to confirm that the umpire is recording it correctly.

Then, if the sub is illegal, enforce any penalties only upon appeal.

Did I get what he was telling us right, or did I misunderstand how to handle this?

Or was I maybe just getting drowsy near the end of that two-and-a-half hour meeting?