trouble on API usage (user.login on Zabbix 2.2)

[shaopeng]

This is my first time to try the API, and here is the command I tried:
curl -i -X POST -H 'Content-Type:application/json' -d '{"jsonrpc":"2.0","method":"user.login","params":{ "user":"Admin","password":"zabbix"},"auth":null,"i d":0}'...