You need a QR code from the Railplanner-app to have a valid tickt.

Check that the Railplanner-app is updated to the latest version. There was a bug some days ago that prevented the QR code from showing but that was quickly corrected in a new version of the app.

All Journeys must be added to the Trip that you have connected to your pass. 

I have the latest version of the app.  I have the train I am taking as a journey.  I have a seat reservation and supplement that I purchased separately from the eurail website--i have hardcopy of that plus the receipt is uner My Account under bookings.  On My Trip the journey shows a requirement for a seat assignment and supplement.  The toggle switch is grayed out and also if I start from My Pass and try to add journey, when I select it nothing happens.  I cannot figure out how to get the journey to add to the pass.  Any ideas?  Thank you!

I got it to work.  Thanks for the help!

FYI: reservations and the pass are completely separate. You can add any journey to your pass, whether you have a reservation or not. If it doesn't work, then the cause must be something else.