well you might know this already, but you would need to supply and enable the necessary things for it to execute the script. for example, if you want to do recall, you'll need to place an arbiter for a computer player, enable/researched the ability as default, and set the energy cost to 0 so it can cast it). don't think the hero arbiter can do the recall script.
anyway if you done that, then probably you do have too many scripts firing at one time.
for the nuke it won't create the nuke if the unit limit is reached, and without that, the script can't be fully executed.
QUOTE
- Nuking -
*Use the direct "Build nuke at location" AI to force the computer to build a nuke in a silo (I don't think your suppose to preserve this trigger that this AI is in)
*With a nuke ready now use the "Target nuke at location" AI to force the computer to use one of its ghost to target the first unit that gets in its way with a nuke (you can preserve this trigger)
*A ghost will target invincible units with a nuke despite the fact the nuke won't even hurt it
*Sometimes even what the computers default race can matter to get this to work so set it to terran if it doesn't seem to work with the others
well here's a tutorial link for getting computers to use certain things. just scroll down to the abilities you're looking for.
http://www.staredit.net/index.php?tutorial=175