I spent a good amout of time chasing down why the sheet index was not working and acting strange. It wouldn't let me add more sheets or reorganize sheets. I ended up finding that the Number of Digits setting on the folder was only set to 1. After getting over 9 sheets in the folder it stopped working. If there had been an error message to alert me to this issue it would have saved me a lot of time and saved me from submitting a service ticket.