Trying to Deserialize a SOAP envelope using DataContractSerializer in C#

I've got this working using the XmlSerializer, but wanted to compare performance using the DataContractSerializer. I know I'm close, because I'm at least getting somewhat of an object graph back, but not any data. A sample of XML I'm trying to deserialize looks like this:

<soap-env:Envelope xmlns:soap-env="http://ift.tt/sVJIaE">
    <soap-env:Header/>
    <soap-env:Body>
       <n0:OperationalDataProvisioningFetchDataDirectResponse xmlns:n0="http://sap.com/bw" xmlns:prx="proxy">
           <BinaryObject>Binary Data Goes Here</BinaryObject>
           <XMLFormatUsedCode>ABAP_XML</XMLFormatUsedCode>
       </n0:OperationalDataProvisioningFetchDataDirectResponse>
    </soap-env:Body>
</soap-env:Envelope>

My classes to deserialize into look like this:

[DataContract(Name = "Envelope", Namespace = "http://ift.tt/sVJIaE")]
public class Envelope
{
    [DataMember(Name = "Header", Order = 0)]
    public object Header;

    [DataMember(Name = "Body", Order = 1)]
    public EnvelopeBody Body;
}

[DataContract(Name = "Body")]
public  class EnvelopeBody
{
    [DataMember(Name = "OperationalDataProvisioningFetchDataDirectResponse", Order = 0)]
    public FetchDataDirectResponse FetchDataDirectResponse;
}

[DataContract(Name = "OperationalDataProvisioningFetchDataDirectResponse")]
public  class FetchDataDirectResponse
{
    [DataMember(Name = "BinaryObject", Order = 0)]
    public string BinaryObject;

    [DataMember(Name = "XMLFormatUsedCode", Order = 1)]
    public string XMLFormatUsedCode;
}

When I run this and attempt to deserialize this is all i get: