uinavigationcontroller back button reloads the current loaded screen - iphone

Question

Im having a strange bug in my code while working on an app for iphone. I am creating a navigation controller and putting it within my tab bar controller and then when i move from my initial screen to a secondary screen the back button on the secondary screen points to itself. so when back is pressed it just reloads itself and then the next time it is pressed it goes back to the first screen.
UINavigationController *nav1 = [[UINavigationController alloc] init];
// create the initial views for each nav controller
SearchViewController *searchView = [[SearchViewController alloc] init];
searchView.title = #"Search";
//place all the viewcontrollers on the nav controllers ready to view
[nav1 pushViewController: searchView animated:NO];
//create tab bar out of above nav controllers
UITabBarItem *item = [[UITabBarItem alloc] initWithTitle:#"Search" image:[UIImage imageNamed:#"search.png"] tag:0];
nav1.tabBarItem = item;
UITabBarController *tbc = [[UITabBarController alloc] init];
tbc.viewControllers = [NSArray arrayWithObjects:nav1, nil];
//
[nav1 release];
above code is in appdelegate for initial set up of nav + tab controller
SecondScreenViewController *sVC = [[SecondScreenViewController alloc] init];
sVC.title = #"Screen 2";
[self.navigationController pushViewController:sVC animated:YES];
[sVC release];
above is the code in the search view controller that loads the second screen / viewcontroller to the nav controller. But the back button at the top of screen 2 has the word screen 2 in it and when i press it once it reloads itself and then the back button says search (which is the title of first screen) . this time pressing it brings it back to the first screen.
Im just confused why the back button displays the view controllers own title name and reloads itself. I dont have any other code in these screens really, they are just blank screens with labels displaying which screen is there while i learn how to use it correctly

Answer 1

In the Apple Docs for UINavigationController for the designated initializer
- (id)initWithRootViewController:(UIViewController *)rootViewController
it is stated that:
Every navigation stack must have at least one view controller to act as the root.
I would recommend trying to initialize your UINavigationController with a rootViewController.

Answer 2

TiltedWindmill, I've experienced that problem before. In my case, in my head, I wanted to do this:
( > = pushing view controller )
Start at MapViewController > Details About An Attraction for a clicked pin on the map > MapViewController > Then pushing another DetailsViewController.
In my MapViewController, this view controller was registered for a notification. Theoretically, I thought I was navigating like this Map > Details View Controller > Map > Details View Controller. The thing was, whenever I tapped on the pin on the map, the Notification was fired and both copies of MapViewController that was on the navigation stack responded to the notification.
As a result it pushed two copies of the same DetailsViewController. So the real navigation was like this:
Map > Details View Controller > Map > Details View Controller copy1 + DetailsViewController copy2
*> = Second details view controller was pushed ontop of the previous one but not visible to the eye.
When I went to press the back button, it popped DetailsViewController copy2 and showed the same view controller (DetailsViewController copy1).
I fixed it by telling my MapViewController to unsubscribe from the notification on the event viewDidDisappear.
Not sure if you understood that :P