Using Sign-up Administration with more than one content type

Hi

I am using sign up on more than one content type.
Everything works fine except under Sign Up Administration (admin/content/signup), only one of the content types are displayed.
How do I display both content types?

(Users can still sign up for the other content type. However, as these don't appear on sign up administration, the only way to see the sign-ups is to check each page of the content type, which, as you can imagine, is very time consuming when you have lots of content).

Any pointers would be most appreciated.