I am trying to create a subscriber using the SalesForce Marketing Cloud/Exact Target SOAP API. My subscriber is successfully being created, but they are not appearing in the specified list (only appear in the "all subscribers" bucket). Below is the body of my SOAP envelope. Any help would be appreciated!
<s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<CreateRequest xmlns="http://exacttarget.com/wsdl/partnerAPI">
<Options>
<SaveOptions>
<SaveOption>
<PropertyName>*</PropertyName>
<SaveAction>UpdateAdd</SaveAction>
</SaveOption>
</SaveOptions>
</Options>
<Objects xsi:type="Subscriber">
<Client>
<ID>555</ID>
</Client>
<ObjectID xsi:nil="true">
</ObjectID>
<EmailAddress>some email address</EmailAddress>
<Lists>
<ID>123456789</ID>
</Lists>
<Attributes>
<Name>First Name</Name>
<Value>First</Value>
</Attributes>
<Attributes>
<Name>Last Name</Name>
<Value>Last</Value>
</Attributes>
</Objects>
</CreateRequest>
</s:Body>