Fade sketch stuck in mathematical loop
It seems like the problem occurs when brightness is a lot higher than potValueConverted. 

For example, lets say our brightness=100, potValueConverted=50, this triggers the latter "if" condition, i.e.


  brightness >= potValueConverted


and at the next iteration, brightness = 105 (or 95), both of which will satisfy the condition for fadeAmount to flip its polarity, thus resulting in the brightness value oscillating between 105 and 100 (or 100 and 95).
This results in the LED getting stuck at the same level of brightness.

a quick hack fixes this problem (as far as I can tell)

 if (brightness &lt;= 0 ) {
    fadeAmount = 5;
  }
 if (brightness &gt;= potValueConverted +5 ) {
    fadeAmount = -5;
  }


**note the +5 for the second if statement is to ensure that the brightness value does not become negative.