title: Unable to cast object of type 'ASP.XXX_master' to type 'XXX.MasterPage'
body: <p>I want to access a specific control in a master page from the page which use it so i write the following code line :</p>
  
  <pre><code>this.Master.FindControl("pnl_Buttonss").Visible = false;
  </code></pre>
  
  <p>Now </p>
  
  <p>I get the following exception from the page .designer.cs :</p>
  
  <pre><code>Unable to cast object of type 'ASP.masterpage2_master' to type 'GuideUI.MasterPage'.
  </code></pre>
  
  <hr>
  
  <pre><code> public new GuideUI.MasterPage Master {
              get {
                  return ((GuideUI.MasterPage)(base.Master));
              }
          }
  </code></pre>
  
  <p>this 's the code which throw the exception .How to fix this error</p>