Help! completing mission after killing boss

Hi guys, so im pretty new to ue4 and im a bit lost. Basically I have created an enemy(right now its just a box), this enemy can die if I shoot it 5 times. What I want is to be able to trigger a mission success custom event once this enemy dies. This custom event is in another blueprint so im not sure how to have it detect that the enemy has died.

Thank you.

This is what ive been trying so far but it doesnt work. Any ideas?