Event dispatcher crash

I have a blueprint “bpBall”. In this blueprint I have event dispatcher “BallDestroyed”:

30666-balldestroyed.jpg

In the level blueprint I handle this event:

30667-handleevent.jpg

Everything works fine, until I reopen the Editor. Then it crashes when I start play, or when I try to recompile the level blueprint or when I try to delete this node in blueprint.
Error:
Unhandled exception at 0x000007FECFCECCCD (UE4Editor-BlueprintGraph.dll) in UE4Editor.exe: 0xC0000005: Access violation reading location 0x0000000000000008.
Callstack:

>	UE4Editor-BlueprintGraph.dll!000007fecfcecccd()	Unknown
 	UE4Editor-BlueprintGraph.dll!000007fecfcbd0db()	Unknown
 	UE4Editor-UnrealEd.dll!000007fed171283e()	Unknown
 	UE4Editor-Kismet.dll!000007fece727780()	Unknown
 	UE4Editor-Kismet.dll!000007fece732651()	Unknown
 	UE4Editor-Kismet.dll!000007fece736136()	Unknown
 	UE4Editor-Slate.dll!000007fed25c05d3()	Unknown
 	UE4Editor-Slate.dll!000007fed26098cc()	Unknown
 	UE4Editor-GraphEditor.dll!000007fed04151cf()	Unknown
 	UE4Editor-Slate.dll!000007fed25a8be2()	Unknown
 	UE4Editor-Slate.dll!000007fed2565f4d()	Unknown
 	UE4Editor-Slate.dll!000007fed256788a()	Unknown
 	UE4Editor-Slate.dll!000007fed260a209()	Unknown
 	UE4Editor-Slate.dll!000007fed25fb0c8()	Unknown
 	UE4Editor-Core.dll!000007fed571e6c4()	Unknown
 	UE4Editor-Core.dll!000007fed570a1fb()	Unknown
 	UE4Editor-Core.dll!000007fed571fbbb()	Unknown
 	UE4Editor-Core.dll!000007fed5706cf2()	Unknown
 	[External Code]	
 	UE4Editor-Core.dll!000007fed5720076()	Unknown
 	UE4Editor.exe!FEngineLoop::Tick() Line 2193	C++
 	UE4Editor.exe!GuardedMain(const wchar_t * CmdLine, HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, int nCmdShow) Line 131	C++
 	UE4Editor.exe!WinMain(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * __formal, int nCmdShow) Line 191	C++
 	[External Code]