Could Not Deserialize JSON Object

We are trying to consume WCF service which returns employee details in JSON Format.

like:

{"d":[{"_type":"Employee:#","BigThumbNailURI":null,"ID":1,"Name":"E1"},{"_type":"Employee:#","BigThumbNailURI":null,"ID":2,"Name":"E1"}]}

From VB.net code behind when I am trying to deserialize it it's stating that

"Expecting state 'Element'.. Encountered 'Text' with name '', namespace ''."

Deserialization code snippet:

Dim serializer = New DataContractJsonSerializer(GetType(List(Of Employee)))
Dim memoryStream = New MemoryStream()
Dim s = msg.Content.ReadAsString()
serializer.WriteObject(memoryStream, s)
memoryStream.Position = 0.......