polling notification cannot be enabled

hi ,
i have created a basic polling notification ,and i enabled it and the whole process worked fine (pub doc ,trigg and flow service) ,

------ and then i deleted my basic notification and created again , now the problem is when i schedule the notification and save it , i am not getting the link for enabling the polling notification…and also i am unable to delete the polling notification.
any thoughts or suggestions on why we having this problem,