Refuses to have the object selected

Basically, I want to send a message to a user interface from a game world object. when I go to the message It tells me to select a name and object. I select both but the object doesn’t stay making the message not work. Usually, I just refresh Flowlab and it works but for this, it’s not the case. My Game is here and the problem lies in the object Cave2

I looked over the game and everything seems to be working for me. When I collect the pickaxes it spawns a cube inside of the “blockholder” but I would probably make it so when the block (any of them) break it will send a message to the blockholder so it will then say you have a block.
Other than that I couldn’t find anything wrong.