Battle of Helm's Deep (or Siege, I forget which)

I had 3 friends of reasonable experience join me in the lobby to start the Helm's Deep scenario. We rarely play scenarios, so there is a chance that there is something we just don't understand.

We each selected a strat, and started playing. It was a joke - the Uruks eventually overran the Elves along the Deeping Wall, as expected, but the castle itself was never touched. As the Elves, I was able to hold on to both the Deeping Ramp and the Inner Ramp while Rohan slowly began dominating the game. Rohan and Elves were running PD, Dunlendings were running RA, and the Uruks were running BK.

At the beginning of Turn 5, the opening message announced that there were 70 new units near Battlements, but none ever appeared near any of the cities that are labeled "battlements" (there are several). The Uruks controlled the caps of all countries that had "battlements" cities along the Deeping Wall, which were initially Elf territories (I don't know if that matters). We don't even know who was supposed to receive the units!

I was just wondering if there were known glitches with the scenario, or whether it is supposed to be run without strats, or what...it was pretty disappointing.

I'd like to learn how to make scenarios so that I could play around with the Helm's Deep sequence and make it more interesting. The units look good to me, as do the number of scenario units added in turn 1, but the relative incomes are grossly out-of-whack. Rohan can build units throughout the game, i addition to the scenario units it receives, while everyone else is negative after turn 1 or turn 2. It's no contest - Rohan wins outright every time.

Help?