Hi Jamila,
The script is now working, the fix was ok, I only see a possible misconfiguration now. On the Theme Options -> Slick layout panel make sure the dimension is correct for the item width. I currently see a value of “300” without the dimension, I guess you meant “300px” there: http://i.imgur.com/DWlj0Qe.png
That should do the trick 🙂