Olympic Restaurant Corp. v. Bank ofWheaton, 251 Ill. App. 3d 594, 599 (1993). Here, contrary to Groshek and similar cases, we hold that, pursuant to the reasoning of Hubble v. O'Connor, 291 Ill. App. 3d 974, 980-81 (1997), a contract was formed. McGrath accepted the Patels' offer. Upon that acceptance, a contract was formed.

¶ 27 We find the contract was formed when plaintiff's offer was accepted on March 22, 2013, and therefore the rider was not a counteroffer, but a request for modifications under the terms of the contract. See Hubble v. O'Connor, 291 Ill. App. 3d 974, 981 (1997) (a counteroffer rejects an offer only when made before a contract is formed). ¶ 28 Defendants also argue that the contract was null and void because it had not been accepted until after the acceptance period had passed. Plaintiff, on the other hand, contends that the parties waived the acceptance period by engaging in a course of conduct which indicated their desire and intent to be bound by the contract.

In its motion to dismiss, Chicago Title argued that the plaintiff had waived the contractual provision requiring it to pay only subcontractors by specifically directing Chicago Title to pay Tenant Improvements. Chicago Title argued further that, because it relied on the plaintiff's direction to pay Tenant Improvements, the plaintiff was estopped from asserting any claim against Chicago Title based on those payments. Waiver and equitable estoppel are affirmative defenses and under Illinois law must be affirmatively pled or they are waived. Hubble v. O'Connor, 291 Ill. App. 3d 974, 684 N.E.2d 816 (1997). In this case, Chicago Title did not raise these defenses in an answer but used them as the basis of its section 2-615 motion to dismiss.

¶ 14 Defendant argues that because granting the seller the right to refuse the bid would constitute a different term other than the terms the parties agreed to at the auction, the Sales Contract actually constitutes a counteroffer, which defendant was not required to accept. See Hubble v. O'Connor, 291 Ill. App. 3d 974, 980 (1997) ("An acceptance conditioned on the modification of terms in an offer generally constitutes a rejection of the offer and becomes a counter-offer that the original offeror must accept before a valid contract is established."). We disagree. ¶ 15 In this case, because there is no dispute that defendant was bound by the Terms of Sale or that the auction was an absolute sale, plaintiff accepted defendant's offer when the auctioneer's gavel fell. "A counter-offer rejects an offer only when made before a contract is formed.

Illinois courts have recognized that, to be enforceable, a real estate sale contract must: (1) be memorialized in a written document or documents; (2) contain a description of the property and the sales terms, including price and manner of payment; and (3) bear the signature of the party to be charged. Hubble v. O'Connor, 291 Ill.App.3d 974, 983, 225 Ill.Dec. 825, 684 N.E.2d 816, 823 (1997).          A review of the correspondence between the parties makes it clear that there was no real estate sales contract formed between them.

In support of that contention, appellants cite a law review article that, in turn, cites cases from Illinois and New Jersey. See Noble-Allgire, Attorney Approval Clauses in Residential Real Estate Contracts-Is Half a Loaf Better Than None? (2000), 48 Kan.L.Rev. 339, 374, citing Hubble v. O'Connor (1997), 291 III.App.3d 974, 225 III.Dec. 825, 684 N.E.2d 816, and Kutzin v. Pirnie (1991), 124 N.J. 500, 591 A.2d 932.

"' [Citations.]" Hubble v. O'Connor, 291 Ill. App. 3d 974, 987, 684 N.E.2d 816, 825-26 (1997). To prevail on an estoppel theory, "the plaintiff must have `had no knowledge or means of knowing the true facts.' [Citations.

Under Illinois law, "[t]he test used to evaluate an estoppel claim is whether, considering all the circumstances of the specific case, conscience and honest dealing require that a party be estopped." Hubble v. O'Connor, 684 N.E.2d 816, 823 (Ill.App.Ct. 1997). In Hubble, the state appellate court set forth the elements a plaintiff is required to show in order to make out an estoppel claim:

Mem. at 28.) Under Illinois law, "[t]he test used to evaluate an estoppel claim is whether, considering all the circumstances of the specific case, conscience and honest dealing require that a party be estopped." Hubble v. O'Connor , 291 Ill.App.3d 974, 984–85, 225 Ill.Dec. 825, 684 N.E.2d 816, 824 (Ill.App.Ct. 1st Dist.1997) (citing Carey v. City of Rockford , 134 Ill.App.3d 217, 218, 89 Ill.Dec. 278, 480 N.E.2d 164, 165 (Ill.App.Ct. 2d Dist.1985) ). In Hubble, the Illinois appellate court set forth the elements a party is required to show in order to make out an estoppel claim:

"[S]imply because a communication discusses the possibility of modification does not necessarily mean that the communication is a demand for modification." Hubble v. O'Connor, 684 N.E.2d 816, 821 (Ill. App. 1997) (quoting Restatement (Second) of Contracts § 39, comment b (1981) ("A mere inquiry regarding the possibility of different terms, a request for a better offer, or a comment upon the terms of the offer is ordinarily not a counter-offer[ ] because such a response "may manifest an intention to keep the original offer under consideration")). An acceptance which requests a change or addition to the terms of the offer will be construed as a counteroffer only when "the acceptance is made to depend on an assent to the changed or added terms.