Browsing to https:///sdk gives blank page ?

We are running vCenter 5.1 (VCenter Server Appliance)  A programmer is attempting to utilize the API to pull information on ESXi hosts and VM's. When we point a web browser at https://<hostname>/sdk/ we get a blank page. I do get info if we browse to https://<hostname>/Folder/   and https://<hostname>/mob/

Anyone have thoughts as to what might be the problem? Searched around a lot an couldn't come up with an answer.  Since I am not a programmer, the docs on the API are a little vague to me.

Thanks,

Mike