serializing multi level structure in Visual basic.net web service

[rgerla]

I'm trying to serialize a compount structure set for a web service, the
sturctures are something like this:
Public Structure UserPhone
Public phonenumber As String
Public phonetype As Char
End Structure

Public Structure userdata
Public firstname As String
Public lastname As String
Public Phonenumers() As UserPhone
End Structure

Public Structure UserDiscipline
Public PrimaryUsers() As userdata
Public AlternateUsers() As userdata
Public Delay As Integer
Public Fillcount As Integer
End Structure

Public Structure UserActivation
Public PrimarySequence As String
Public AlternateSequence As String
Public Duration As Integer
Public CallApprove As userdata
Public Disciplines() As UserDiscipline
End Structure

and when asking the Webservice to show the contract for het specified method
he is showing only the first 2 levels

<activation>
<PrimarySequence>string</PrimarySequence>
<AlternateSequence>string</AlternateSequence>
<Duration>int</Duration>
<CallApprove>
<firstname>string</firstname>
<lastname>string</lastname>
<Phonenumers>
<UserPhone xsi:nil="true" />
<UserPhone xsi:nil="true" />
</Phonenumers>
</CallApprove>
<Disciplines>
<UserDiscipline>
<PrimaryUsers xsi:nil="true" />
<AlternateUsers xsi:nil="true" />
<Delay>int</Delay>
<Fillcount>int</Fillcount>
</UserDiscipline>
<UserDiscipline>
<PrimaryUsers xsi:nil="true" />
<AlternateUsers xsi:nil="true" />
<Delay>int</Delay>
<Fillcount>int</Fillcount>
</UserDiscipline>
</Disciplines>
</activation>

I would really want to have the complete multi-level structure in XML does
anybody have a suggestion on doing this?