The query parameters look accurate in your API call. I would certainly simplify the API call initially as you build out any automation you are putting together to make sure there are results as previously mentioned. I do not have the complete context to what you are putting together, but you may also want to review:
Confirm that you have the correct org_id in the o query parameter
Validate the HTTP Status Code you receive after making the request
Confirm you are making a GET HTTP request to the servers resource
Confirm you are providing the right authentication token
What language or tool are you using to make the request? You can also review some examples depending on what you are using to get the expected response.