SW-DK-TM4C123G: Question regarding ADC peripheral address (to get it enabled)

This concerns programming the ADC. 

First the basics:

CCS version: 7.3.0.00019 

PC OS: Win10

TI Code base: TivaWare_C_Series-2.1.4.178

Data sheet: Tiva™ TM4C123GH6PGE Microcontroller-15033.2672 Copyright © 2007-2013 (it came in a USB drive in the box)

I am trying to setup ADC0 to read voltages. Specifically simple circuit where a potentiometer is connected between the 3.3v and ground, and its output is input to PE6 (AIN21).  file for a  pic.

The reference code is based on: C:\ti\TivaWare_C_Series-2.1.4.178\examples\peripherals\adc\single_ended.c

Here it is:

The code as shown above results in displaying mostly 0's and occasional 1's from #268.