Don't Panic

Two objects won't Group (under Arrange menu.) What's gone wrong?

It happened again to me: panic, two objects won't group...

I was half way to quitting Pages and posting a question on the internet, when I remembered - they both have to be fixed on the page. One of mine was inline.

Go to Wrap inspector,
change inline object to fixed on page.
Group.

So, when you're in a hurry to finish a project, tired and hassled remember: most problems have simple solutions.

Step back and look again at what you're doing.