Play icon not visible on image target in Vuforia Video Playback in Xcode

I'm experimenting vuforia video playback in xcode. I successfully run the sample application. Now Im trying to change the database. I have loaded the database as mentioned below.

// load the data associated to the trackers - (bool) doLoadTrackersData { return [self loadAndActivateImageTrackerDataSet:@"vuforia.xml"];; }

There are two image targets in vuforia.xml database (vuforia.dat) named twitterlogo and appzone. I can detect the appzone image target but I can't detect appzone image target. As well as play icon is not visible on appzone image target. If I click on the appzone image target, relevant video is played. Now I need to know why twitterlogo image target is not detected and play icon is not visible on the image when target is detectedCan anyone help me to fix this issue.

// VideoPlayerHelper to use for current target     int playerIndex; 

    if (strcmp(imageTarget.getName(), "twitterlogo") == 0)     {         playerIndex = 0;     }

    else if (strcmp(imageTarget.getName(), "appzone") == 0)     {         playerIndex = 1;     }