Dear @ Jocelyn Ireson-Paine
I am not have many years experience in Moodle.
But my working with same web service.
As per my experience, You need to assign role from user->role
and also from web services->
http://docs.moodle.org/20/en/Using_web_services
Best of luck.
Using same code I am facing error
Notice: Array to string conversion in ....\moodle\bpms\lib\filelib.php on line 3000
Any one have any idea please share.