Inventory UI with UMG - Click on button don't work

OKi i think that i understand this a little. But still got problem with first picture.

https://dl.dropboxusercontent.com/u/26116566/UnrealEngine/InventorySlotWasClicked.png

On every click in button i call ButtonWasClicked and I should get this call on Bind Event who is connected to Array of buttons. But it never happend.