regular expressions for file types - jQuery uploader issue

I'm trying to implement the jQuery uploader into a webpage. All the files are in the right places, and we're using the standard regular expression that comes with the software (/.+$/i), which I believe should accept all files.

But when you try and upload a file, it quits straight away and gives Error: filetype not allowed. The filename I'm tryin开发者_运维百科g to upload is 1234.jpg.

Anyone any ideas? I've tried Googling it, but not come across the same problem with this specific uploader. Any help would be appreciated!

If the file is zero bytes then it won't upload.