FIX THE BUILDING UP DATE I CANT PLACE THE WALLS THE WAY I WANT TO

When building, if I try to delete a wall, it refuses to disappear, and if I try to get rid of it, it gives me an "error" message. I then have to hit the undo button repeatedly until the wall reappe...

I am a bit unsure if this is a bug or a problem with my network. But when I entered build mode and was going to place down a wall, but I was only able to place down that pole. I tried to drag it to...