How to compile for iPhone 4 - ios5

Question

here is my problem:
I have a fully working app which runs quite perfect on my iPhone 4S running iOS 5.1.1.
Now Apple rejected my app because they found that the app crashed upon launch on iPhone 4 running iOS 5.1.1. What do I have to do to compile for the iPhone 4? I can't really test it because I only have an iPhone 4S to my disposal. I already did some tweaking in the project settings and added armv6. What else do I have to do?
I symbolicated the crashreport I got from apple as you can see below.
However, the problem remains the same. I can not figure out why my app does not run on an iPhone 4. I found one piece of code that is mentioned as #6 of the last exceptions.
It is located in ViewController.m. This is my code at the specified line:
self.player =[[MPMoviePlayerController alloc] initWithContentURL:[NSURL fileURLWithPath:url]];
Last Exception Backtrace:
0 CoreFoundation 0x3742088f __exceptionPreprocess + 163
1 libobjc.A.dylib 0x35125259 objc_exception_throw + 33
2 CoreFoundation 0x37420789 +[NSException raise:format:] + 1
3 CoreFoundation 0x374207ab +[NSException raise:format:] + 35
4 Foundation 0x37c0805f -[NSURL(NSURL) initFileURLWithPath:] + 79
5 Foundation 0x37c07ffb +[NSURL(NSURL) fileURLWithPath:] + 43
6 Podman 0x00021feb -[ViewController viewDidLoad] (ViewController.m:43)
7 UIKit 0x3112dc8b -[UIViewController view] + 167
8 UIKit 0x3112c461 -[UIWindow addRootViewControllerViewIfPossible] + 45
9 UIKit 0x3111ee87 -[UIWindow _setHidden:forced:] + 295
10 UIKit 0x3118f7d5 -[UIWindow makeKeyAndVisible] + 25
11 UIKit 0x3112ce6d -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1633
12 UIKit 0x311267dd -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 409
13 UIKit 0x310f4ac3 -[UIApplication handleEvent:withNewEvent:] + 1011
14 UIKit 0x310f4567 -[UIApplication sendEvent:] + 55
15 UIKit 0x310f3f3b _UIApplicationHandleEvent + 5827
16 GraphicsServices 0x33b3622b PurpleEventCallback + 883
17 CoreFoundation 0x373f4523 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 39
18 CoreFoundation 0x373f44c5 __CFRunLoopDoSource1 + 141
19 CoreFoundation 0x373f3313 __CFRunLoopRun + 1371
20 CoreFoundation 0x373764a5 CFRunLoopRunSpecific + 301
21 CoreFoundation 0x3737636d CFRunLoopRunInMode + 105
22 UIKit 0x3112586b -[UIApplication _run] + 551
23 UIKit 0x31122cd5 UIApplicationMain + 1081
24 Podman 0x00021e7b main (main.m:16)
25 Podman 0x00021e30 start + 40