Serialize all elements with namespace prefix

[Don]

I am calling a web service that requires all elements to have a namespace (or
alias) prefix before all elements. Here is an example of xml that works
correctly:

<SOAP-ENV:Body>
<m:VINValidationRequest xmlns:m="http://...">
<m:requestHeader>
<m:RequestingApplicationCd>Test</m:requestingApplicationCd>
</m:requestHeader>
</m:VINValidationRequest>
</SOAP-ENV:Body>

The xml stream that gets generated from my .Net call to the web method does
not contain the namespace prefix though (the m: is omitted).

<SOAP-ENV:Body>
<VINValidationRequest xmlns="http://...">
<requestHeader>
<RequestingApplicationCd>Test</requestingApplicationCd>
</requestHeader>
</VINValidationRequest>
</SOAP-ENV:Body>

Can someone tell me how to get this namespace in each element when the .Net
serialization function is invoked?

Thank you