function GetTrackDetail() {
    var text = document.getElementById('textfield');
    var validtext = text.value;
    if (validtext == "" || validtext == " ") {
        alert("You need to enter in AWB No.!!!");
        text.focus();
    }
    else {
        window.location = "TrackTrace.aspx?AwbNo=" + window.document.getElementById("textfield").value;
    }
}