Rome Total War - Sieges - Gateway

This really, really, really, really, really, really, really, really, really, really, really, really annoys me (the amount of really's shows my frustration), let me set the scene.

I'm assaulting a city. Approaching from the east and west with two battering rams and equal amounts of my army on both sides. I have hoplatai manning the two rams and two units of velites backing each ram up. We approach the gates and cause 50-100 casualties from my velites on the enemy hoplites on the opposite side of each of their gates. Now as soon as the gates are breached, I make my hoplites drop the rams and charge through the gates and assault the units on the other side. Now this is the annoyance...

After about 5 minutes of fighting at the gates, I send in some spanish mercenaries to back up the east gate, as my hoplites there are getting a hammering as they have attracted about 4 different enemy units to themselves. For some reason however, they don't want to go through the gate? Every time I click for them to attack the units, they just mill around the gate entrance and don't do anything. All-the-while my hoplites are losing men and are close to routing.

My game is still running and the above description is as far as I have got, if anyone's got any tips for my current assault or future ones, please respond quickly.

Thanks

Try clicking behind the hoplites or dragging with the right mouse inside the walls.

Sounds like a pathing problem. This usually happens when most of the unit is on the ground but 1 man or moreis left on the walls. Basically do as above poster stated or click on any piece of ground not occupied by an enemy unit.