I'm working through the Control Fun project in Apress's Beginning iOS 5 Development and ran into a bit of a problem. After connecting the two switches (leftSwitch and rightSwitch) I encountered a build failure. I traced the failure to having mistyped rightSwitch as rightSwirch. I went through my code and made the corrections. The build now succeeds but the program crashes after trying to load the iOS simulator with the following error Code: Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<BIDViewController 0x6bbde50> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key rightSwirch.' I've been through my code a few times and can not find anymore references to rightSwirch and the fact that the build is successful makes me think I got them all. I tried deleting the control and all reference to it and then adding the control and making the connections again but I'm getting the same SIGABRT error. Any ideas?