HCM emp Rest Service PATCH problem

Summary

Running into an issue with PATCH operation.

Content

Has anyone had a successful PATCH operation for updating emails? I have followed the example in https://docs.oracle.com/cloud/latest/globalcs_gs/FARWS/Updating_Employee_Information.html, but no luck for me. I see a Not Implemented/Unsupported Request 501 error.

HTTP/1.1 501 Not Implemented
Server: AkamaiGHost
Mime-Version: 1.0
Content-Type: text/html
Content-Length: 521
Expires: Fri, 02 Dec 2016 16:12:25 GMT
Date: Fri, 02 Dec 2016 16:12:25 GMT
Connection: close

My curl statement is as follows:

curl -i -u "<user>" \
-H "Content-Type: application/vnd.oracle.adf.resourceitem+json" \
-H "Effective-Of: RangeMode=CORRECTION" \
-X PATCH \
-d '{ "WorkEmail" : "James.Harrington123.student@ni.com" }' \
"