I am using a Dropship menu, where u drop the unit you want to use, and it casts the spell.
What I want to know is: Can you detect how many units are in the dropship? In my map you start with an empty dropship and have to find items. I have it cleverly set up like this:
CONDITION:
-Current Player brings exacly 1 civilian to location get_item
-Current player brings at most 9(drop ship + 8 units inside) men to location use_spell.
ACTION:
-Give all any units owned by player 1 at location use_spell to player 3(neutral)
-create 1 zergling for player 3 at location use_spell
-Run Ai script enter transport at location use_spell
-Give all any units owned by player 3 at location use_spell to player 1
Preserrve Trigger.(for testing)
I have this on Hypertrigger, and the dropship is moved to location use_spell, repeatedly.
Currently as my trigger sits, it does not detect units inside the dropship. It does the first part correctly, but when the dropship becomes full, it keeps creating zerglings until there are 9 there...
Question: Why does it create 9 extra zergling if I specified AT MOST 9 units(counting the dropship)?? If I change it to AT MOST 8 units, it creates 8 lings max. And is a dropship considered "men" ??
There is a thread,
http://www.staredit.net/index.php?showtopic=2291 by Tuxedo Templar, that talks about the dropship menu. I also tried downloading the map Coordinates by (U)Bolt_Head in that thread, but could not open it in Editor to maybe get an idea of how to figure this out. So I tried playing it in SinglePlayer but it crashes my desktop and screws it up, so I have to restart my PC.

Did I mention I hate BB/UBB code?? ;P HTML is so much simpler.
Ok first of all, you do not need to give the dropship to another player to load the units into it. Get that out of your head.
Second, unless the trigger you posted belongs to P3 (and I believe some AI scripts don't work for neutral players, but I don't know about the 'Enter transport' one), the AI script will only work for the current owner of the trigger, and not P3.
Third, I think doing a quick 'give unit' in the middle of an AI script will actually interrupt the script, but don't take me to the bank with that one (I haven't tested that thoroughly).
Fourth, you want to use 'brings at most 8' instead of 9, because if you have 9 units (including the dropship) then the dropship is already full, and you'll be making another zergling to load in it, which won't work.
Last, if the location 'use_spell' is air only, and you're executing an 'Enter transport' AI script to load ground units into your dropship, then I THINK that might not work because it's being activated for the air only location, asking the transport to load ground only units... if you see what I mean. If it does work, then I'm wrong, but at least you'll want to try using a normal location (air and ground) if you can't get it to work the other way.
If you're using player 3 to load the ship so the units won't activate the spell trigger for the current player... don't do that. Instead, use a switch or set a counter for the current player to a non-zero number while the dropship is (re)loading, and set the spell trigger's condition to activate only when that switch is cleared or the counter is 0. Set the switch/counter back to cleared/0 when the unit has successfully (re)loaded into the dropship, to complete the triggers.