I think you need the check box for sparge using equal size batches checked.
However
If the grain bill is to large, I think BeerSmith only does one round because there is so much water in the grist. I have Scotch that came in at 1.104 and it only had one sparge round even with a 120 min boil. It was a 20# grain bill and I could have made two beers with this thing. The Scotch Ale and then an Old Ale with the second running's. But I did not want to have an all day brew session.
Cheers
Preston