title: asp.net mvc listbox options are selected even though selected value is not defined
body: <p>I am working with asp.net mvc. I have a listbox in my view. The options in this listbox are always selected on page load. I have not defined any selected value for this listbox. Can anyone tell me why this is happening?</p>
  
  <p>Here is the code </p>
  
  <pre><code>          @{
                 Dictionary&lt;string, string&gt; Options = new Dictionary&lt;string, string&gt;();
                 ddlOptions.Add("1", "1");
                 ddlOptions.Add("2", "2");
                 ddlOptions.Add("3", "3n");
                 ddlOptions.Add("4", "4");
             }
             &lt;td&gt;@Html.ListBoxFor(model =&gt; model.AvailableProducts, 
             new MultiSelectList(Options , "Key", "Value"), 
             new { size = "6" })
  </code></pre>
  
  <p>model.AvailableProducts is a list of strings:</p>
  
  <pre><code>        List&lt;string&gt; product = new List&lt;string&gt;();
          product.Add("1");
          product.Add("2");
          product.Add("3");
          product.Add("4");
  </code></pre>