Android AlertDialog won't display

I have an app that shows a welcome screen via an alert dialog. I use the following code in the onCr开发者_运维问答eate method of the Activity:

wsBuilder = new AlertDialog.Builder(this);
wsBuilder.setIcon(android.R.drawable.ic_dialog_alert);
wsBuilder.setTitle(R.string.instructions_title);
wsBuilder.setMessage(R.string.welcome_1);
wsBuilder.setPositiveButton(R.string.ok,
    new DialogInterface.OnClickListener() {
      public void onClick(DialogInterface dialog, int which) {
          dialog.dismiss();
      }
    });
wsBuilder.show();

When I start the app, most of the time the screen darkens like it does when the dialog is going to display, but the dialog never shows up. The screen just stays darkened and none of the touch events get through. I can click the back button on the phone to dismiss the dialog and then the app works like normal, but I can't figure out why the dialog doesn't fully display. Once in a while the dialog actually displays, but most of the time it doesn't.

Any help in running down this issue would be greatly appreciated.

OnCreate may not be the best place for it as the application is loading try using it onStart

public void onStart()
{
    //Your code here
}

Activity would be better for wellcome screen.