Change Image Brush

Hi! I have some problem. I want change Image Brush in game.
Here is code line that do that action:

BackgroundImage->SetBrush(BackgroundEvenBrush);

BackgroundEvenBrush is:

UPROPERTY(EditAnywhere, Category = “WTLContactListItemWidget Variables”)
FSlateBrush BackgroundEvenBrush;

and BackgroundImage is

UImage* BackgroundImage;

But when i start a game, it’s crash. The log is written that the error in the method in which my code line is written above.
Help me! How change brush of image?