Issue with sd_utility.php

[mollcons]

When I run sd_utility.php I get only this error:

./sd-utility.php

Using production server.
Using timezone UTC
sd-utility.php utility program API:20141201 v0.28/2015-12-04
Using database information from ~/.mythtv/config.xml
PHP Fatal error: Uncaught Error: Call to undefined function simplexml_load_file() in /export/home/root/mfdb/mfdb-json-API-20141201/functions.php:537
Stack trace:
#0 /export/home/root/mfdb/mfdb-json-API-20141201/sd-utility.php(220): getLoginFromFiles()
#1 {main}
thrown in /export/home/root/mfdb/mfdb-json-API-20141201/functions.php on line 537

What is wrong? How do I rectify this?