I'm getting SIGABRT when I try to load a video (objective-c)

So the problem I am having is that when I try to load a video this way:

-(void) viewDidLoad
{
MyManager *sharedManager = [MyManager sharedManager];
[super viewDidLoad];
NSString *tempName = sharedManager.vidName;
NSLog(@"%@", tempName);

//This is where the problem is being caused
NSString *url = [[NSBundle mainBundle] pathForResource:tempName ofType:@"mp4"];
//This is where I'm getting the SIGABRT thrown
MPMoviePlayerController* theMovie = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL fileURLWithPath:url]];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(movieFinishedCallBack:) name:MPMoviePlayerPlaybackDidFinishNotification object:theMovie];
theMovie.scalingMode = MPMovieScalingModeAspectFit;
[theMovie.view setFrame:self.view.bounds];
[self.view addSubview:theMovie.view];
[theMovie play];

}

I am getting a SIGARBT thrown where I specified in code due to a NSException. However, If I simply write out the string, as follows:

- (void)viewDidLoad
{
MyManager *sharedManager = [MyManager sharedManager];
[super viewDidLoad];
NSString *tempName = sharedManager.vidName;
NSLog(@"%@", tempName);

//This is the line I changed
NSString *url = [[NSBundle mainBundle] pathForResource:@"vid_name" ofType:@"mp4"];

MPMoviePlayerController* theMovie = [[MPMoviePlayerController alloc] initWithContentURL:[NSURL fileURLWithPath:url]];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(movieFinishedCallBack:) name:MPMoviePlayerPlaybackDidFinishNotification object:theMovie];
theMovie.scalingMode = MPMovieScalingModeAspectFit;
[theMovie.view setFrame:self.view.bounds];
[self.view addSubview:theMovie.view];
[theMovie play];

}

the code works perfectly fine. What could the problem be? I NSLog tempName to make sure that it is holding the correct string and it is. Also, sharedManager.vidName is a NSMutableString. This is the only problem left holding me back from finishing my Senior project and graduating college, so ANY help would be greatly appreciated. Thank you.

Here is what I'm getting in the log:

2012-03-26 22:04:52.115 SeniorProject[20502:207] Barbell Incline Bench Press - Medium Grip
2012-03-26 22:04:52.120 SeniorProject[20502:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
*** Call stack at first throw:
(
0   CoreFoundation                      0x00fb15a9 __exceptionPreprocess + 185
1   libobjc.A.dylib                     0x01105313 objc_exception_throw + 44
2   CoreFoundation                      0x00f69ef8 +[NSException raise:format:arguments:] + 136
3   CoreFoundation                      0x00f69e6a +[NSException raise:format:] + 58
4   Foundation                          0x007e3ab6 -[NSURL(NSURL) initFileURLWithPath:] + 90
5   Foundation                          0x007e3a44 +[NSURL(NSURL) fileURLWithPath:] + 72
6   SeniorProject                       0x000105f4 -[Video viewDidLoad] + 420
7   UIKit                               0x000ef089 -[UIViewController view] + 179
8   UIKit                               0x000ed482 -[UIViewController contentScrollView] + 42
9   UIKit                               0x000fdf25 -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 48
10  UIKit                               0x000fc555 -[UINavigationController _layoutViewController:] + 43
11  UIKit                               0x000fd870 -[UINavigationController _startTransition:fromViewController:toViewController:] + 524
12  UIKit                               0x000f832a -[UINavigationController _startDeferredTransitionIfNeeded] + 266
13  UIKit                               0x000ff562 -[UINavigationController pushViewController:transition:forceImmediate:] + 932
14  UIKit                               0x000f81c4 -[UINavigationController pushViewController:animated:] + 62
15  SeniorProject                       0x00005998 -[ExerciseList goToVideo:] + 328
16  UIKit                               0x0003f4fd -[UIApplication sendAction:to:from:forEvent:] + 119
17  UIKit                               0x000cf799 -[UIControl sendAction:to:forEvent:] + 67
18  UIKit                               0x000d1c2b -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527
19  UIKit                               0x000d07d8 -[UIControl touchesEnded:withEvent:] + 458
20  UIKit                               0x00063ded -[UIWindow _sendTouchesForEvent:] + 567
21  UIKit                               0x00044c37 -[UIApplication sendEvent:] + 447
22  UIKit                               0x00049f2e _UIApplicationHandleEvent + 7576
23  GraphicsServices                    0x011ea992 PurpleEventCallback + 1550
24  CoreFoundation                      0x00f92944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
25  CoreFoundation                      0x00ef2cf7 __CFRunLoopDoSource1 + 215
26  CoreFoundation                      0x00eeff83 __CFRunLoopRun + 979
27  CoreFoundation                      0x00eef840 CFRunLoopRunSpecific + 208
28  CoreFoundation                      0x00eef761 CFRunLoopRunInMode + 97
29  GraphicsServices                    0x011e91c4 GSEventRunModal + 217
30  GraphicsServices                    0x011e9289 GSEventRun + 115
31  UIKit                               0x0004dc93 UIApplicationMain + 1160
32  SeniorProject                       0x00001b39 main + 121
33  SeniorProject                       0x00001ab5 start + 53
)
terminate called after throwing an instance of 'NSException'

Check out console log and see if it says something like this:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'

If so, then sharedManager.vidName is definitely different from @"vid_name", and the path cannot be successfully found. Maybe @"vid_name.mp4"? Then you probably just have to replace

NSString *url = [[NSBundle mainBundle] pathForResource:tempName ofType:@"mp4"];

with

NSString *url = [[NSBundle mainBundle] pathForResource:tempName ofType:nil];

Give it a try.