Does the run score?

[dommigirl]

We play slow pitch softball under ASA rules. Here's my situation:

One out, man on first and third. Batter hits line drive to Short stop, man on first took off for 2nd, saw the ball caught, turns back for 1st. Short stop throws to first for the force out. 3rd base runner went home.
the ump let the run score, stating that he crossed before the out. our view is that is was a force out so the run shouldn't count.

what do you say?

thanks
Shelli