Ps own approximately 16 acres of land in Kane County. They reside on the property and use it for their gradually developing agricultural and landscaping business. D constructed and owns a golf course known as Mill Creek Golf Club. The course is leased to American Golf Corporation, which performs daily tasks such as collecting greens fees and maintaining the course. Ds caused and allowed golf balls to continually invade Ps' property. Ps' business is seasonal and coincides with the golf season. Due to the constant stream of uninvited, wayward golf balls, Ps have not been able to use significant portions of their property. Ps contend that D’s intentional acts constituted both an intentional trespass and a private nuisance. Ps sought an injunction against Ds and sought compensatory and punitive damages. Ds alleged that Ps were estopped from bringing their claims by virtue of Ps' conduct, memorialized in a prior agreement. At trial evidence on how the property was developed was given. Ps told the developer that they did not want housing adjoining their property. Ps then chose the fairway to abut their property's western boundary and made other requests that were granted. P also publicly endorsed the change in plans. According to Ps, they did not negotiate any specific land use of Ds' property. Rather, Ps only wanted assurances from defendants that the use of their property would not impact plaintiffs' property use. Ps never requested that a golf course-especially a golf course fairway-be located adjacent to their property. An agreement was signed by the developer and Ps. When the course opened, Ps began to find golf balls on their property. During the 1997 and 1998 golf seasons, plaintiffs collected 2,128 golf balls on their property. Some of these had landed as far away as 300 feet from the property's western boundary. Ps’ residence and other existing buildings are not in the affected area. No person on plaintiffs' property had ever been struck by an invading golf ball. Persons on Ps' property would be in no more danger of being struck than those walking in other areas in the development. No one had ever told Ps that the golf balls inhibited the property's suitability for being farmed. Ps stopped growing the alfalfa crop not because of the golf balls, but rather because they planned to use that land for cultivating plants for their nursery business. No one had ever told Ps that the golf balls prevented them from placing greenhouses in the area or cultivating plants for their nursery business. The trial court entered judgment for Ds. Ps appealed.