websocket getTrades - internal server error

[jrobinson01]

I'm trying to use the getTrades method via websocket. I get an error response Internal server error with code: 500. An example request:

{
   "id": "getTrades_7005.489999894053",
    "method": "getTrades",
     "params": {
        "symbol":"LTCUSD",
        "by":"id",
        "limit":1000
     }
}

I've also tried by:'timestamp' and the from and till parameters but each attempt results in the same error response.