I can't get ajax ready state 4?

[Dashkhuu K]

I can't get the ready state 4.
when i try this, its working fine and alerting each readystate and 'well done':
function stateChanged()
{
alert(HTTP.readystate);
if(HTTP.readystate==4)
alert('well done');
}
but following is not working, it had to alert 'well done' when completed, but it's not alerting anything:
function stateChanged()
{
if(HTTP.readystate==4)
alert('well done');
}
Does any body know this issue?