Using 1.7.2, but problem also happened with 1.7.1

If a registered user uploads an image, they enter the details, (author name, created date, description, etc), but "Author" never gets populated - it always appears as N/A

Example: http://www.scribcam.co.uk/gallery/pictu … ategory/76

Is there something I'm missing? I would like it so a user who is logged in and uploads a photo gets their username as the author!

Maybe I'm just missing something simple...