why am I not getting a response for dog sitting request?

When the time is up, then the request officially ends. Of course, it can always be resurrected, but I question why you would want to hire a sitter that hasn't answered you. Hopefully, you've reached out to several sitters, as Rover advises, to meet and discuss your dog sitting needs. One of Rover's performance measures is responsiveness and you will see it on the sitter's profile.