Hi Gkhan,
We need more information about the lesson you created.
Kindly email us at
support[at]brillkids[dot]com with the following information:
1. Which exact playback settings did you apply and what type of media files have you've added to your "file" (also, did you make a "category," a "playlist," or a "course"?)
2. If you can, please export your file and attach it to your email
3. Do confirm if LR crashes when you play your lesson, and if you do see any particular error message. If you did see an error message, make sure you take note of the full error (or take a screenshot of it).
4. Lastly, attach your diagnostic report. For instructions on how to create a diagnostic report, see:
http://support.brillkids.com/entries/20438423-How-to-Create-a-Diagnostic-Report-for-your-BrillKids-Learning-System