Numbers won't make a PDF

Hi,

All of a sudden I've been having trouble exporting a Numbers doc to a PDF. Used to be able to do it all the time but now it won't allow it.

First problem, is says that I can't create a PDF file name longer than 31 characters. Never used to have this problem. I could always name it basically whatever I wanted with as many characters I wanted. So I trim down the file name to be 31 characters long and then I run into this problem...

Second Problem, I try to make the file and it gives me this message: "The file '(insert file name here).pdf' doesn't exist.

So, I don't know whats happened. It used to be as easy as pie to export to pdf but now it seems like it has become the most difficult thing in the world. Very frustrating. Can anyone help please?