ROSbridge: "Service does not exist"

edit

I am trying to call the service /cac/GetMapInfo in a stage simulator from ROSbridge in a simple test program:

from websocket import create_connection
import json

test_json3 = { 
    "op": "call_service",
    "service": "cac/GetMapInfo"
}
test_json = json.dumps(test_json3)
ws = create_connection("ws://localhost:9090")
ws.send(test_json)                 
while(1):
    print(ws.recv())               # print what ever is published on topic

However, the websocket returns this:

call_service InvalidServiceException: Service /cac/GetMapInfo does not exist

Running the script results in:

{"values": "Service /cac/GetMapInfo does not exist", "result": false, "service": "cac/GetMapInfo", "op": "service_response"}

But when I run rossrv list | grep cac, the service does exist. Am I missing something? Calling topics through ROSbridge works just fine.