why html action link does not pass the null Id value when use an id
<p>I have used an html action link below</p>

<pre><code> @Html.ActionLink("Book Now", "EnquiryForCruise", "Cruise", new { sid = "stackoverflow" })
</code></pre>

<p>it navigate to correct controller action result but with null id value
path is <code>localhost:15777/Cruise/EnquiryForCruise?Length=6</code></p>

<p>my controller is below</p>

<pre><code>  public ActionResult EnquiryForCruise(string sid)
  {

     return View();
  }
//in here id value is null
</code></pre>

<p>I have worked with this before and those worked fine. I don't have idea why is this.hope your help.</p>