在Error类型的对象上找不到属性？

Question

DetailViewController *dvController = [[DetailViewController alloc] initWithNibName:@"DetailView" bundle:[NSBundle mainBundle]];
dvController.selectedCollege = selectedCollege;
[self.navigationController pushViewController:dvController animated:YES];
[dvController release];
dvController = nil;

我收到了错误

  

在第3行的'DetailViewController'类型的对象上找不到属性'selectedCollege'。