so 9999

I used the number sequnce for Sales Order with the format of SO-#### (4 digit,Smallest 1 and Highest 9999) and when it reached at maximum(9999) I changed the format as SO-##### (5 Digit, highest 99999). angka 9999 artinya But in SO form it is showing Sales Orders upto SO-9999, not newly created after changing the number sequence. so sweet apa artinya