The MCode for horizontal lines doesn't seem to be working. I apologize if this has been reported already but I have tried using 3 hyphens, using 5 hyphens, and making a long line of hyphens across the page and it hasn't ever worked for me. 
Like so:
3 hyphens
---
5 hyphens
-----
15 hyphens
---------------

Edit: Apparently it works after I make an edit to the post! XD
Edit Edit: Or maybe it doesn't always register as the proper code?