But in this separate contract it was agreed that the $2,000 would not be due until the corn had been sold. At the time of the settlement the corn had not been sold and there was nothing in their agreement which would accelerate the obligation. We see no reason here that would cause us to deviate from the general principle that an account stated is deemed conclusive at law and in equity unless fraud, omission or mistake are shown. Wood v. Davis, 2 Ill. App.3d 550, 276 N.E.2d 756; Brown v. Gill, 343 Ill. App. 460, 99 N.E.2d 393. Plaintiff contends that the agreements used in these transactions constituted a lease only of the bins; defendant claims that they established an installment sales contract.