use of dosmetication with a block that stores inventory

Good evening, I have a small question, I may be doing it wrong considering that this is the first time I've used the taming variables, what I want is for the entity to display a GUI that would be a storage block, only when it is already I would have managed to tame the entity, if the entity is not domesticated, it would not have access to be able to store the objects as if it were a chest, could someone please help me.

https://i.imgur.com/JLhorTA.png

I leave attached how I did the procedure if someone could guide me I know it must be a very simple answer but it is the first time I use those variables