Screen recorder stopped when another process exists

Question

I have developed a screen recorder with help of accord package. I have set a button for start and stop recording. And also a rotate button whenever i click rotate button my 3d model will rotate. problem is after start recording i click rotate button it rotate 3d window and stop recording. Except rotate portion all other have been saved. My rotating 3d model is not saved. I checked while debugging my timer is stopped.when rotate happens. What I need to do.

screenRecorder = new DhvaniScreenRecorder();

recordingTimer = new DispatcherTimer();
recordingTimer.Tick += RecordingTimer_Tick;

private void RecordingTimer_Tick(object sender, EventArgs e)
{
    screenRecorder.CaptureFrame();

    // For Adjust frame with output time
    var elapsedMilliseconds = frameTimer.ElapsedMilliseconds;
    var desiredFrameInterval = 500 / 10;

    if (elapsedMilliseconds < desiredFrameInterval) 
        Thread.Sleep((int)(desiredFrameInterval - elapsedMilliseconds));

    frameTimer.Restart();
}

private void btnstop_Click(object sender, RoutedEventArgs e)
{
    isCapturing = false;            
    screenRecorder.StopRecording();
    recordingTimer.Stop();    
}

private void btnSaveVideo_Click(object sender, RoutedEventArgs e)
{
    screenRecorder.StartRecording("E:\\screen_recorded_output.avi", 10);
    frameTimer.Start();
    recordingTimer.Start();
}

After starting the recorder, I need to record my 3d rotation also. vtk is use for 3d