Some menu buttons aren't working

Hi,

I've got two menus of chapter selections and all the chapter buttons work, except for two on the second chapter selection menu. I have no idea why just these two aren't working - all the settings are the same as the other ones, I've checked the button routing and its all in order. The buttons all have the same properties, so these two should work as the others do.

I created the menus in Photoshop and imported them to Encore. There are no transitions, no overrides or anything as far as I know.

In the preview you can click these two chapter buttons with the mouse and they highlight fine. However when I use the arrow buttons in the preview, and when I try it out on a DVD player, the highlights skip from number 9 straight to number 12.

Please help! I feel like I've tried everything

Thank you!