It is a bit hard. I am guessing what you want to do and what your problem is. Hopefully I am close to what you are looking for =/
I think your game is spawning many BulletFX simultaneously. For me, the On create condition becomes a bit troublesome. C2 seems to be confused which one to pick during the On Create event when more objects are created in the same tick.
What I do is adding an instance variable to BulletFX, let's call it TriggerCheck. TriggerCheck has value zero when BulletFX is spawned.
Instead of On Create condition, I would do the following
BulletFX TriggerCheck=0 | System create object etc.
Wait 0 seconds
Set BulletFX.TriggerCheck to 1