[Scripting] Can't get ip from interface

RouterOS Beginner Basics
1

Just bought my first Miktorik, update it’s ROS to 6.0, configured to a simple network - NAT + PPPoE internet through ADSL modem. Trying to execute a simple command:
/ip interface get [find interface=pppoe-out1] addressAnd no luck, no matter what interface name I substitute, result is always null. Please, help me to discover, where I’m wrong.

2 
:put [/ip address get [find interface=pppoe-out1] address]
3

Thanks a lot, it’s help.