Can tables from Pages be reused in Numbers to create graphs? I created a table in Pages '09 and pasted it into Numbers '09 to see if it worked, then I created a graph for it, still in Numbers, but the graph displayed no data as you can see from the screenshot.
So is it because the table came from Pages or there's something I must do before it works ?
I'd like to know if it's safe to create tables in Pages or if they are going to be trapped in it, in that case I'll prefer to create them in Numbers and then paste them into Pages.
I have had the best luck keeping the data in Numbers and only pasting tables and graphs into Pages. But that is because I like the added tools in Numbers and not that I've had any issues pasting back or forth.

I've done a few tests and can't replicate your issue on '09 versions of both iWork programs. Have you experimented pasting the data from pages to numbers as values (or paste and match style)? It is a long shot, but the two things that come to mind is pasting into a new spreadsheet (in case the one you are using has some sort of issue) or pasting data that is somehow formatted to cause an obscure problem.