The sample call posted earlier runs fine on my Grid. Are you certain the values in your variables for name and IP address are correct and for objects you have write access to?

I ran into this same issue. In my case I am using the infoblox plugin for vRA a...

You have to include each individual IP address you want to exclude. You can see an example with a couple IP addresses in the exluide list up above (second grey block from the bottom of MRichard's post).