qtkit - QTmovie can't play video

Question

I'm cocoa beginner , maybe my question is a little stupid :(

• I setup a rtsp server, build in localhost.
• I use qtmovie connect to the localhost to play a video.
• I have two buttons which can switch channel and channel 2 in my rtsp server.

It's fine every time when I click channel 1 and click play button, the qtmovieview controller bar will show negotiate->connecting->setup->playing.

After playing channel 1, when I click channel 2 and play button, the qtmovieview controllerbar only show "connecting", and nothing happen. But sometimes it works !!

Is there any memory allocation problem in the qtmovie? or am I missing something?

Below is part of my code.

(void)play:(id)sender{

    NSLog(@"Play");
    NSURL *url3=[NSURL URLWithString:@"rtsp://127.0.0.1:8554/"];  
    qtmovie=[QTMovie movieWithURL:url3 error:nil];  
    @try {
        [_movieView setControllerVisible: YES];
        [_movieView setMovie: qtmovie];
        [qtmovie play];
        [_movieView display];
                }
    @catch (NSException *exception) {
        NSLog(@"%@",[exception name]);
    }


}

-(IBAction)clickchannel1:(id)sender
{
    NSTimer * timer=nil;

    [_label setStringValue:@"Channel1 Playing"];
    if(channel==2){
        [qtmovie stop];
          [_movieView setMovie:nil];
        [timer invalidate];
        timer = nil;
        CloseChannel(channel);
    }
    channel = 1;
    OpenChannel(channel);
    timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(showBufferLevel:) userInfo:nil repeats:YES];

}

-(IBAction)clickchannel2:(id)sender;
{


    [testThread release];
    NSTimer * timer=nil;
    [_label setStringValue:@"Channel2 Playing"];
    if(channel==1){
         [_movieView setMovie:nil];
        [timer invalidate];
        timer = nil;
        CloseChannel(channel);
    }
    //[qtmovie play];
    channel = 2;
    OpenChannel(channel);
    timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(showBufferLevel:) userInfo:nil repeats:YES];
}

Thank you for your help !!