Trouble counting to seven

[whaddayouknow]

I think we blew one last night and I looking for where we went wrong. (FED, if it matters.)

We had five linemen in standard set. L side had one wide out with L signalling right arm out for 'off the line.' LJ side had two players just to the tackle's right. To me (the U) they looked off the line. There was also a wide out on the LJ side. LJ had both arms out for 'one off/one on'.

At the snap, I dropped a flag. After the play, I reported the infraction to the R and we marked off the penalty and replayed the down. This negated a large gain.

A couple of plays later, we had a hurt player. During the time out, the LJ said to me, "You know I had two on the line on that penalty. I was giving you the arm back for the one off the line and with the arm forward I was holding two fingers out, to signal 'two on'."

Ouch! Okay, messed up and move on. But what lessons are there to learn?

1. Better pregame: The wingmen did tell me that if they had two men on, they would not hold both arms on one side, but would hold up one arm with two fingers out. This is not our usually singal but was good for me. However, we did not discuss this 'three people' mechanic. I guess we should have.

2. What is my responsibility as an umpire if I throw a flag in this situation? Should I check with wing men to see if they really did have people on or off? Perhaps not the solo receiver like the L had above, but should I verify when I have multiple receivers lined up?

3. If a wingman has two receivers 'on', should he notify the U if the flag is thrown?

(I realize if multiple are 'on' then the inside one is covered and not really a 'receiver'.)

Comments or suggestions? I'm just trying to get it right next time.