AI can't use a ram

Was playing as Pritanoi and I captured the southeastern province in britain(can't remember the name). Later a rebel spawned nearby and sieged the city, built a ram and assaulted. During the battle he didn't use the ram. One of the units was still moving the ram and they were coming right towards the gate at the beginning but then the whole army just stopped right before the gate. They stood still in range of the city towers until I got bored and opened the gate for them.

Update. Same campaign, another rebel army spawns and sieges another city. It's the second province from the top in Britain(sorry I'm horrible with names). I had the highest level walls I think. They build a ram and a ladder and assaulted. It was one buggy battle!

Screenshot gallore incoming.

Spoiler Alert, click show to read: 

So first up the ladder guys get stuck at the top of the ladders. They still keep losing men every now and again, I'm not sure if they are being shot by tower arrows(I didn't see any) or whether my men get a kill every once in a while(they didn't seem to fight at all).


Here's an interesting one. The unit I have selected was standing behind the main gate. Since the ladder seemed bugged and the ram wasn't moving in either, I again decided to open the gate for the enemy to speed up the battle. So I clicked the unit to move outside the city and they decided to take this scenic route using the enemies ladder.


So I moved the unit back behind the wall. In this picture I have the original "wall defender" unit selected. Since the enemy wasn't coming to them, they decided to take the fight to the enemy. Oh and now the ladder started to work(at least every once in a while). I tried to go through the gate again by moving the unit farther away from the enemy ladder and then clicking outside the city. So they all piled up against the gate without opening it. I clicked again to move outside and finally the gate opened and the tribesmen got out.


Well, most of them. Also notice that the enemy units did not react to the open gate at all(unlike in the previous battle where they immediately rushed in). In the background you can see the ram and a chariot unit.


By this time the "on again/off again" ladder has allowed most of the enemy unit go get up to the wall. Notice though that they aren't actually fighting my men. At around this point the battle started to lag like hell. I sped up the game and in the end the wall defenders routed. They rallied at the town square. Then the unit outside the gate routed. but by this point the gate had already closed and they couldn't get back in(the gatehouse was not captured by the enemy yet). At this point the other unit routed again and the battle ended.

I never had the problem with the ram...but I noticed that the troops on the ladders move when I withdraw my troops from the wall.