Why some replays work and others don't

[cl2007]

I was wondering if anyone knows anything about how replays work... specifically why some replays are in sync and others are not.

Part of the reason I love playing RTW (and now with darthmod) is that after I win a heroic battle, I could watch it all over again like a movie. When you're fighting a tough battle, you don't really have time zoom in and watch the action since most of the time you're busy giving orders.

Anyways, I've noticed with darthmod that there are some patterns regarding why some replays work and some don't. For instance, almost everytime i play as romans the replays would not work. Replays playing against barbarians often don't work either. Thus I often limit myself to playing as Greeks or Seleucid.

Also, I have this replay of the most interesting and hardest heroic battle I've ever played (Greeks vs Thracians and Pontus) which worked yesterday, and yet it doesn't work today! I know replays aren't always 100% accurate because they don't record the movements and actions of every individual soldier, but this replay has nothing to do with that. I noticed that the CPU changed their orders early on for certain units compared to yesterday (e.g., thrace made their first attack with their scout cavalry on my goldshield today instead of my regular hoplites which they did yesterday, and both the goldshield and hoplites were units that were far away from each other), and even that one change in orders caused everything else to be messed up.

Later, I quit RTW and then restarted it again, and decided to watch the replay one more time to see if it would work yet. It didn't work, but this time, the CPU changed their orders *again*. After watching a few times, I noticed that the cpu consistently gives out one of two or three patterns of the same wrong orders randomly.

So again, I was wondering if anyone could shed some light on this issue? Clearly there must be some pattern to this! Is there some units that I should avoid perhaps? I'm willing to just not use them if it can increase the chances of an epic battle being recorded accurately

[DARTH VADER]

I know that replays will not work if you have changed something in game files after the battle.
Or if 2 players play in LAN and have incompatible versions will soon get desync.