function doNegotiable(isChecked) {
    var txtDayRate = document.getElementById('txtDayRate');
    if (isChecked) {
        txtDayRate.disabled = true;
        txtDayRate.value='Negotiable';
    }
    else {
        txtDayRate.disabled = false;
        txtDayRate.value='';
        txtDayRate.focus();
    }
}