Problem with auto_increment and categories

Hi,

I've just installed PunBB 1.2.12 with a few modifications, but have encountered a couple problems.

The first major issue was with the database structure. For some reason, the table indexes didn't have auto_increment 'on', so I manually set them on the tables which looked like they needed auto_increment. If anyone has a reason for why there's no auto_increment on and which tables should have them on, please let me know!

Second, when I add a new category, the display number defaults to '0' -- it's not incrementing. I can't set auto_increment on for the display number for a category in the table, b/c that column isn't the index.

Does anyone know what kind of problem I'm having?

Please help! Thanks!