To send the window as back ground

To send the window as back ground i have used the code lines in my application
as..

TApaTask task(iEikonEnv->WsSession( ));
task.SetWgId(CEikonEnv::Static()->RootWin().Identifier());
task.SendToBackground();

But in real ,When i send the sms to the cell containg the above code from other cell
it is not workin..(Need to open the application for working)while i want it to work
that application without open to it..

can anyone sugget me ,what precautions should i have to take????

thks in advance......