Hello, there is a problem with UMG, I have a main menu and game menu (screenshots will be attached) .If you select New Game, then the transition from one level to another successful, but if you go to the main menu, the error takes off (screenshot as well attached). Perhaps I'm doing something wrong? How can I open level with help of C ++?

Main Menu https://drive.google.com/open?id=0By...eDA&authuser=0
Game Menu https://drive.google.com/open?id=0By...TlU&authuser=0
Errors https://drive.google.com/open?id=0By...cDg&authuser=0
Main Menu Widget https://drive.google.com/open?id=0By...dUk&authuser=0
Main Menu Level BP https://drive.google.com/open?id=0By...MXc&authuser=0
Game Menu Level BP https://drive.google.com/open?id=0By...dGs&authuser=0
Call Game Menu https://drive.google.com/open?id=0By...LXc&authuser=0
Move to Main Menu https://drive.google.com/open?id=0By...TUk&authuser=0