Modulator Synth _Crash when set note off with note one

I have made a sequencer using a modular synth actor component, and as long as i’m not setting the "Note Off"everything works fine, but if I stop the note (which sounds much better) it play with no problem but after a few seconds , it crashes and UE4 close itself .
I use the same Modulator Synth for every note. I store note and parameters for each step in lists and then i set those parameters to the synth at each step.