You mention you set the trigger value in "Creation Code" - is this Instance Creation Code or in the Create Event? It shouldn't matter, but it would be good to confirm.
I just checked the engine myself, and it seems to work fine; can you confirm your code looks like the following?
Spike Instance Creation Code
Trigger Instance Creation Code
spikeUp Create Event & spikeUp Step Event
Your step event looks correct, so we just need to find where the problem is. Which kind of spike are you using for this trigger? is it a spikeUp, or a different kind of spike? Is it a custom spike object? If so, show me the Create Event for it, I want to make sure trg is being initialized.