Engage Interaction Missing

I created several interactions in Engage while in the PPT file itself.  I went back several days later to add the narration and I get a pop up message saying "Unable to access Interaction XX hame.  Please locate the interaction.  Then, I'm promted to broswe within my file directories in my PC.  I get this message whether I launch engage from within Artciulate or clikc on the button for Engage on the slide itself.

I have been creating the Engage ineractions while in my slides and had success doing that in the past.  What is the problem with the program still showing the interaction on my slide but saying it can't locate it?

Thanks,

Karin