function RequiredField(control, messageBox)
{
    var element = document.getElementById(control);
    if(element == null)
    {
        SetVisibility(messageBox, true);        
    }
    else if (element.value == '')
    {
        SetVisibility(messageBox, true);
    }
    else
    {
        SetVisibility(messageBox, false);
        return true;
    }
    return false;
}

function RequiredRadioField(radioName, messageBox)
{
    var arr = new Array();
    arr = document.getElementsByName(radioName);

    for(var i = 0; i < arr.length; i++)
    {
        var obj = arr.item(i);
        if(obj.checked)
        {
            SetVisibility(messageBox, false);
            return true;
        }
    }
    SetVisibility(messageBox, true);
    return false;
}

function SetVisibility(field, visible)
{
    var element = document.getElementById(field)
    if(visible)
        element.style.display = '';
    else
        element.style.display = 'none';
}