Anyone have trouble commanding a lot of units via triggers?

Im working on a part of my RPG that's kind of like helms Deep. You're defending a little fort from 2 enemy armies. Anyway I'm running into problems getting the attacking army to move to where I want them to. Most of them do go, but others stop along the way, or just don't move from the building where they are spawned.

I have 4 barracks where units are created by triggers. I made a trigger that creates units, but it's an If/Then/Else. After that I made a trigger that makes the last created unit attack-move to a region where the fort's gate is. And like I said, some units don't go.

Later on I added the last created unit to a Unit group. Then made all unit from that group attack, and flash a speech indicator (so I could know who's in the group), every few seconds. I noticed that very few of them were flashing, so not everyone was getting added to the group. I made another trigger, when a enemy unit enters the map, to add him to the group. And another trigger that picks all units in the map, and adds them to the group. And still, they don't all flash, or attack. Is there a limit to how much people can be in a Unit Group Variable? I still got some more ideas to try, but If anyone has some insight, I would like to know.

i've had that problem before too, i fixed it by making a ton of unit groups, so try using more unit groups. you could also try having a trigger that does

every x seconds of game time
pick unit of type X belonging to player and order unit to attack move to region X

ok, so not the most creative solutions, and there even kinds obvious but i thought that i might as well try to help.

The problem is that only 12 units may be in a unit group at a time. If you ordered a unit group of 50 to move somewhere, only 12 would.

StormWraith has the idea that I use...

Unit Group - Pick all unit (whereveror some type), and order picked unit to do (action)

Wait X seconds.......Repeat.