i found the problem:
you have to disable the release trigger on map init
if u add a debugging message in every trigger to see when they run you will notice that the cast and release trigger always fire together, so the spell ends immediately
also you need a delay after casting before you enable the other trigger, just add Wait 0.25 seconds between turning off the one and turning on the other trigger and give your ability a cooldown of 1sec or anything that you cant cast it too early when no trigger is enabled
some side notes:
- you should stop the timer when the release trigger runs
- when i load the map the dummy doesnt have the aura, instead he has the ability unknown (A00R)
- also in the cast trigger it says "Create 1 _ for (Owner of ...." i put the dummy in there
- you should use the even "Unit starts the effect of an ability" instead of "Unit starts casting an ability", else you can produce bugs
- you are leaking a location, use the following custom script at the end of your triggers "ShelterRelease" and "ShelterTimer":
call RemoveLocation(udg_CasterPosition)