Set Audience for Quick Launch Navigation Links Programmatically

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Administration;
using Microsoft.SharePoint.Navigation;

namespace ConsoleOperations
{
    class TargetAudienceToNavigationNodes
    {
        static void Main(string[] args)
        {
            using (SPSite site = new SPSite("http://localhost:5030"))
            {
                using (SPWeb web = site.RootWeb)
                {
                    SPNavigationNodeCollection nodeColl = web.Navigation.QuickLaunch;
                    SPNavigationNode nodeHeader = new SPNavigationNode("TestNode", @"Lists/Tasks/AllItems.aspx", false);
                    SPNavigationNode node = new SPNavigationNode("TestNodeFirst", @"/Lists/Tasks/AllItems.aspx", false);
                    nodeHeader = nodeColl.AddAsLast(nodeHeader);
                    nodeHeader.Children.AddAsFirst(node);
                    node.Properties.Add("Audience", ";;;;GroupName");
                    node.Update();
                    web.Update();
                }
            }
        }
    }
}

We must specify the 4 colons (;) before group name....