Stop matinee in background and start playing?

Hi I am a bit new to unreal engine

I have a widget menu with a start game button. In the background I added a Matinee.

I want to press the start button and making the matinee to stop and start the game. Is this possible? I tried this but I think it doesnt work :

A - In my Widget blueprint I have my OnClicked button, then I create a event dispatcher

B - An then in my level blueprint I bind the event and make the matinee to stop. But it gives a Accessed None error.

Any help?