Having Root Issues

This probably simple, or I'm just not doing something right.
I'm using CASUAL root to attempt root on my AT&T S4 and here is the log:[*] Waiting for device...
Waiting for ADB device connection. When Windows 8.1 recognizes the device, we will continue. Don't touch anything.[*] Device found.[*] Pushing exploit...
4856 KB/s (1283460 bytes in 0.258s)[*] Pushing root tools...
6875 KB/s (96260 bytes in 0.013s)
4769 KB/s (1578585 bytes in 0.323s)[*] Pushing recovery to device...
5012 KB/s (10484224 bytes in 2.042s)[*] Rooting phone...
[+] This may take a few minutes.

[-] Failure.

installing superuser to system partition
/system/bin/sh: su: not found

# begin build properties

# autogenerated by buildinfo.sh

ro.build.id=KTU84P

ro.build.display.id=KTU84P.I337UCUFNJ5

ro.build.version.incremental=I337UCUFNJ5

ro.build.version.sdk=19

ro.build.version.codename=REL

ro.build.version.release=4.4.4

ro.build.date=Tue Aug 4 23:52:59 KST 2015

ro.build.date.utc=1438699979

ro.build.type=user

ro.build.user=dpi

ro.build.host=SWDE2213

ro.build.tags=release-keys

ro.product.model=SAMSUNG-SGH-I337