How to get XML node value using a XPATH SSIS XML Task

I am trying to use a XML task in SSIS to get a session ID value from this XML:

<?xml version="1.0" encoding="utf-16"?>
<AuthenticationResult xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<authenticated xmlns="[link]">true</authenticated>
<sessionId xmlns="[link]">0000-0000000-00000000000-000000</sessionId>
<loginid xmlns="[link]">000000</loginid>
<login_name xmlns="[link]">[Username]</login_name>
<user_nbr xmlns="[link]">0000</user_nbr>
<partition_id xmlns="[link]">3</partition_id>
<is_parent_mail_user xmlns="[link]">0</is_parent_mail_user>
<parent_user_id xmlns="[link]" />
<user_id xmlns="[link]">[username]</user_id>
</AuthenticationResult>

However I cant get the task to return the Session ID

Task setup:

Operation Type: XPATH
SourceType: File connection
Source: testfile.xml

SaveOperationResult: True
DestinationType: Variable
Destination: User::SessionID
OverwriteDestination: True

SecondOperandType: Direct input
SecondOperand: //sessionId

Namespaces: (Collection)
PutResultsInOneNode: False
XPathOperation: Values

No namespaces are specified.

I have googled all around but I can't figure out why it is not working...