Q: how do I import a diagram from Pages document to a Keynote presentation

I have a desktop Mac

I have a Keynote presentation and I want to import a diagram that was developed on Pages

I was able to drag the diagram into the presentation previously but now that process no longer works

My Keynote and my Pages have both been altered (not sure how or why in the last two days and I am now having difficulty with both.

When I save the documents I am not able to retrieve them and in some cases not able to manipulate them

At this point I have both the Keynote and the Pages document complete and now I need to put the Pages document into the Keynote

Suggestions?