Google Plus API - BadRequest on all public requests

[GoogleCodeExporter]

What steps will reproduce the problem?
1. I have enabled Google+ API
2. I have requeste a SimpleKey 
3. When I call the API endpoint from my PHP script I get error like this

 { ["error"]=> object(stdClass)#2 (3) { ["errors"]=> array(1) { [0]=> object(stdClass)#3 (3) { ["domain"]=> string(11) "usageLimits" ["reason"]=> string(10) "keyInvalid" ["message"]=> string(11) "Bad Request" } } ["code"]=> int(400) ["message"]=> string(11) "Bad Request" } }

https://www.googleapis.com/plus/v1/people/+DavideCarbonini/activities/public?key
={key}

I've tried read from other https hosted jsons around the internet and found no 
problem at all

I've set to allow my SimpleKey available to all IP addresses

Please Help,

Thanks

Original issue reported on code.google.com by noreply....@gmail.com on 17 Apr 2015 at 3:11