Hey Rob,
In the original question you were using colon’s instead of equal signs in your query params, so I figured that was your problem. The query looks right now, other than you need to specify a specific course id number in place of “:course_id” in the url (and you don’t need other_param, I was just using that as an example of how you combine two different query params together).
If it still fails with a real course id number in the url, check your logs and look for an error message and a stack trace, that might be helpful in debugging further.
Simon