I came across this during my install and deploy of rockstor.
If you select a pool --> add a share (it defaults to the pool name) and then create your share it creates it and drops you back to the shares page.
If you click on add a share again, it then defaults to the ROOT pool and not the pool you were working with.
It was a bit annoying while I was trying to add 10 new shares to the pool so I could move my data over. I did not catch it the first couple of times and had to go back and remove the shares in ROOT and then make sure to change the pool each time afterwords.