LoadRunner 12 Virtual Table Server - Making API calls

I am using the latest release of LoadRunner 12 and the HP Virtual Table Server. We have the VTS configured and working. I am able to successfully create LR scripts that read and write to/from the VTS using the LR functions.

Now I am trying to build a JAVA client outside of VUGen. I configured access to the API as per instructions in the HP document guide:

VTS3_Communication_Specification_v1.0.docx

When I send a command through the API I can only get back one response:

{"data":null,"status":{"error":"Unexpected token u","code":-20201}}

No matter what I send I get that back from the VTS server. I can see that this is a response from the VTS server and it is formatted in JSON, but this is obviously an incorrect response since returning index:1 should return the first row of data from the VTS (and yes, there is data there. I can see it from the VTS GUI).

I also created a LR WEB Custom Request formatted to send JSON commands directly to the VTS API. Based on everything I read in HP documentation this should be working. Does anyone know what I'm missing here? Is there some additional setup on the server I need to set to allow access to the API or some kind of additional header?

Any help would be appreciated.

	web_custom_request("VTS_Command",
		"URL=http://localvtsserver:8888/api",
		"Method=POST",
		"Resource=0",
		"EncType=application/json", 
		"Body={\"cmd\": \"get\"," 
		      "\"version\": \"1.0\"," 
		      "\"data\": " 
		      	"{\"index\": 1}" 
	          "}",
		LAST);

This is all I see in the VTS log output each time I get that error:

{"level":"info","timestamp":"2015-02-23T19:19:23.383Z","message":"return: {\"data\":null,\"status\":{\"error\":\"Unexpected token u\",\"code\":-20201}}"}