Hello Pavan chittala,
Thanks for reaching out. Which application are you using to call the endpoint? Which auth flow are you using? Did you provide application or delegate permissions to the app? Are you making a POST or GET request? Can you provide the request body when making the Post call? You can find more information on the getschedule call here.
If the reply is helpful, please click Accept Answer and kindly upvote it. If you have additional questions about this answer, please click Comment.
Thanks.