My 4S does registers "Off Line" on my ICloud Locate My iPhone?

Misplaced my IPhone 42 and went to ICloud Find my IHone feature - it displays Iphone Off Line - I found my 4S but the ICloud still shows Off Line and and checked all setting amd am connect - online and USB is plugged into my IMac. What is the cause. Even rebooted and same situation.

I am affaid if I realy lost my phone I will not be able to locate it via ICloud