The chance to find a shiny on PokeMMO is 1/30.000 and nothing affects this chance negatively. We do not apply punishments that would affect your shiny rate.
You can improve this chance by using a Donator Status or a Shiny Charm (around 1/27.000) or using both at the same time (around 1/24.000).
If you have been looking for a shiny, don't give up. It will come soon or later. Good luck!