drive belt instalatio

I have a Craftsman 42" cut model 917. that I bought a couple years ago. It has an automatic transmission. The drive belt broke on it the other day. I got a new belt and I believe I have installed it correctly. But. The idler pulley keeps tension on the belt constantly except when clutch is pushed in. Meaning the tranny pulley spins constantly. Is this the way its supposed to be ? Oh! And here is that letter "N" I forgot to put in the title. LOL!

Makes sense to me.
When clutch is depressed, the belt stops so you can put into or change gears.
Put in forward, release the clutch, and away you go.
Push the clutch in, and you stop.

Does the mower not operate correctly??