Minecraft structure block not working?

I have the following problem, if I put a corner of a structure block and in the other a save block with the same name, it should actually recognize the territory but there it always says: can't recognize construction size - add corners with the same construction name, even though they actually have the same names. In addition, a minecraft is always set automatically: in front of the name when I save it.

You have to put 2 corner blocks!

I had already tried but then the same error message came back

Yes and put the save block on the outside then you have to recognize the construction size

There's a setting called Experimental Gameplay. You have to turn them on