Leon Walras imagined an auctioneer who calls out a price, hears how much everyone wants to buy and sell, and adjusts: if buyers want more than sellers offer, the price is called up; if goods go unsold, it is called down. That search — tâtonnement, French for "groping" — is a real dynamic: dp/dt = λ·(Qd − Qs). Left alone, price glides to the clearing level p* where the two curves cross, and excess demand vanishes.
Clamp the price with a ceiling below p* and the search can never rise to clear: buyers keep wanting more than is offered — a lasting shortage. A floor above p* leaves goods unsold — a surplus. The gap is the price control's own doing, not a failure of the market.
Switch on the production lag and planning happens a step behind, on last period's price — the farmer's cobweb. Now price jumps rather than glides, and stability turns on relative elasticities: the swings shrink when demand out-responds supply, but when supply is the more elastic curve each overshoot is bigger than the last and the market spirals away from equilibrium.
Something in the simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.