NetStream.play() playing after full buffering

programming flash
1

The problem is that FLV movie starts playing after full preloading not streaming.
I am passing FLV with PHP script readfile() method.
Can anybody tell me why my player does not start immediately?

Here is the PLAY part of the code

if (mc_play_pause.currentFrame == 1)
            {
                loader.load(new URLRequest(file));
                mc_play_pause.addEventListener(Event.ENTER_FRAME, playHeadMove);
                btn_volume.addEventListener(MouseEvent.MOUSE_DOWN, startDragVolume);
            }
            if (isplaying == false && ispaused == false)
            {
                isplaying = true;
                ispaused = false;
                ns.bufferTime = 5;
                ns.play(file);
                mc_play_pause.gotoAndStop(10);
            } else if (ispaused == true && isplaying == false)
            {
                isplaying = true;
                ispaused = false;
                ns.resume();
                trace("Resumed from: " + ns.time.toString());
                mc_play_pause.gotoAndStop(10);
            } else if (isplaying == true && ispaused == false)
            {
                isplaying = false;
                ispaused = true;
                trace("Paused at: " + ns.time.toString());
                ns.pause();
                mc_play_pause.gotoAndStop(2);
            }