Tried it myself and got it to work. Your code seems alright, are your ZERGLING units the default zerglings? If not, maybe there's something broken in the unit's data (not sure but I think "Stats - Cargo Size" has to be > 0).
Your nydus worms have no rally point since you are referring to variables that are set a few actions later. Otherwise your trigger should work and unload the zerglings next to it.
Oh, and facing "Position of triggering unit" doesn't work aswell since you don't have a unit related event.
Tried it myself and got it to work. Your code seems alright, are your ZERGLING units the default zerglings? If not, maybe there's something broken in the unit's data (not sure but I think "Stats - Cargo Size" has to be > 0).
Your nydus worms have no rally point since you are referring to variables that are set a few actions later. Otherwise your trigger should work and unload the zerglings next to it.
Oh, and facing "Position of triggering unit" doesn't work aswell since you don't have a unit related event.