Openfire restApi can not add user

I want to use RestApi to add a new user from php by this way:

file_get_contents("http://myip:9090/plugins/restapi/userservice?type=add&secret=mysecretkey&usernam e=kafka&password=drowssap&name=franz&email=franz@kafka.comsecretkey&username=kafka&password=drowssap&name=franz&email=franz@kafka.com");

But it does not add a user, and does not return anything even error.

Even when I type the url in browser it just shows a blank window.

In openfire I chose: Enabled - REST API requests will be processed    &    Secret key auth - REST API authentication over specified secret key.

But still no result.

So what can cause the problem?