Need help in data caching technique

I am implementing how data caching work in asp.net. For that i have kept three button

1)cache date button,

2)currentdate button and

3)Cache Remove button.

If I click on cache date button date will be cached for 2 minitues. if click on current date button current datetime will be displayed, and finally If I click on Remove cache button cache will be removed and fresh cache date and fresh current date will be displayed.

For this I have done the coding but datetime is not caching always it refreshing I mean if datetime is cached for 2 minits and if i click the cached button datetime should not change but in my case its always changing.... Pls somebody modify my code...

  protected void BtnCacheTime_Click(object sender, EventArgs e)
  {      
            Cache.Insert("date",DateTime.Now,null, 
                         DateTime.Now.AddMinutes(2),    TimeSpan.Zero);
            lblCacheDateTime.Text = Cache["date"].ToString();
  }  

  protected void BtnCurrentDate_Click(object sender, EventArgs e)
  {
     lblCurrentDate.Text = DateTime.Now.ToString();
  }  
 protected void BtnRemoveCache_Click(object sender, EventArgs e)
 {
        Cache.Remove("date");
        lblFreshCa开发者_StackOverflowcheDate.Text = DateTime.Now.ToString();
        lblFreshCrntDate.Text = DateTime.Now.ToString();        
 }

Well, for once, you insert DateTime.Now to the cache, and then immediately read its value. What else would you expect?

Next, you shouldn't use TimeSpan.Zero - when setting absolute expiration, you should use Cache.NoSlidingExpiration.