Unable to cast object of type 'System.Object' to type 'Newtonsoft.Json.Linq.JObject'.

[brownrw8]

At line 458 of TestPowerCast/Form1.cs, the cast to JObject is failing.
message = String.Format("The request was not accepted by the PowerCast Hub. Error code: {0} Reason: {1}", response.StatusCode, (**(JObject)responseObject**)["message"]);

Exception thrown is:

An exception of type 'System.InvalidCastException' occurred but was not handled in user code
Unable to cast object of type 'System.Object' to type 'Newtonsoft.Json.Linq.JObject'.