you have a couple of problems in the recordset.
1) Create a new parameter:
Default Value: -1
Run Time Value: $_GET['OrderID']
2) Edit the paramUserID parameter, you currently have the run time value set to use:
it should be set to use the user ID session variable. the example from the tutorial is:
but you will need to double check that is the session ceated by you login page.
to find the session name to use, go to the login page, double click the authenticate user behavior, go to step 3 and make not of the session name for the ID column.