New Session and Web Window

Hi there you pros.
I’m trying to show a Valentina Report (PDF) from my Xojo WebService APP. It’s getting called via HandleSpecialURL, so I need to create a new Session in order to show the PDF. How Can this be done?

Var wSession As WebSession = App.SessionWithIdentifier(“TEST”)
Var context As New WebSessionContext(wSession)
context.Session.ShowURL( mPDF.URL )

Here I only get a NilException