I am new to using APIs in general as well as using Google Analytics API. I am trying to call the google analytics traffic results from a website using google analytics API. When using the rt-source metric I get a missing parameter error. When I try to add the bounce rate as a parameter I get an unknown metric error. Please can someone advise what I am doing wrong or if the problem is at the client's side. See image for example of code.
Thanks in advance!

