Unable to find an element by Id, Name or Xpath using the Webdriver of IE for my webpage

Hi All,

Could you please help me out with the following situation

used tools and technologies

IE 8
selenium webdriver 2.0
Language used C# in VS2010
copied all the dlls from 'selenuim google code site
File : "selenium-dotnet-2.16.0.zip "
url used= checkpointworld.com/maf/app/authentication/formLogin

Code used:

IWebDriver multipleBrowsersDriver = new InternetExplorerDriver();
multipleBrowsersDriver.Navigate().GoToUrl("checkpointworld.com/maf/app/authentication/formLogin");
multipleBrowsersDriver.FindElement(By.Id("uid")).SendKeys("selenium");

The problem I am facing here when i execute the test case using Nunit is
"TestSeleniumWebDriver.webDriverTest.TestCase1:
OpenQA.Selenium.NoSuchElementException : Unable to find element with id == uid"

But when i use the FireFoxDriver or ChromeDriver drive my test executes successfully and able to fill in the text box.

I have tried using different ways by name, xpath but unable to work it out in IE.
I have checked with other sites such as gmail, yahoomail, hotmail everything was working as expected. I do not why for my site it is not working as expected.

thanks in advance for any support you provide.