Conversely, when the language of a contract is unambiguous, the intent of the parties at the time the agreement was entered into must be determined from the language used in the agreement itself, not from the construction placed upon it afterwards by the parties. ( Fitzwilliam v. 1220 Iroquois Venture (1992), 233 Ill. App.3d 221, 230.) An ambiguity is not created merely because the parties disagree as to the meaning of a contract clause.