Adding custom mobile broadband profiles in Win 7

I need to create a custom mobile broadband connection profile on a number of Windows 7 computers. I have learned that this could be accomplished by running the following command:
netsh mbn add profile interface=MobileBroadband Connection" name="ProfileName.xml"
where ProfileName.xml is an XML file created in accordance with the instructions found at http://www.microsoft.com/whdc/connect/wireless/MB_CustGuide.mspx.

The problem is that I always get an error saying "The Profile cannot be loaded" when I run the command.

My XML file looks like this:

 <?xml version="1.0"?>
 <MBNProfile xmlns="http://www.microsoft.com/networking/WWAN/profile/v1">
	 <Name>TestProfile</Name>
	 <ICONFilePath></ICONFilePath>
	 <IsDefault>true</IsDefault>
	 <ProfileCreationType>UserProvisioned</ProfileCreationType>
	 <SubscriberID>123456789012345</SubscriberID>
	 <AutoConnectOnInternet>false</AutoConnectOnInternet>
	 <ConnectionMode>manual</ConnectionMode>
	 <Context>
		 <AccessString></AccessString>
		 <UserLogonCred>
			 <UserName></UserName>
			 <Password></Password>
		 </UserLogonCred>
		 <Compression>DISABLE</Compression>
		 <AuthProtocol>NONE</AuthProtocol>
	 </Context>
 </MBNProfile>

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I have also tried copying a working profile's xml file (from C:\ProgramData\Microsoft\WwanSvc\Profiles), but this also gives me "The Profile cannot be loaded".

Can anyone tell me what I'm doing wrong?