Problem in adding user controls to toolbox programatically

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C#

.NET

Visual-Studio

Hi,
I'm trying to add a new tab and my controls programatically to visual studio 2010.
Its creating tab but its not adding the controls to tab.

//Getting design time environment
          DTE DesignTimeEnvironment = (DTE)Activator.CreateInstance(Type.GetTypeFromProgID("VisualStudio.DTE.10.0"), true);
          //Getting tool box object
          ToolBox VSToolBox = (ToolBox)DesignTimeEnvironment.Windows.Item("{B1E99781-AB81-11D0-B683-00AA00A3EE26}").Object;
          ToolBoxTab MyTab = null;
          string TabName = "MyComponents";
          //checkin if Tab already exists
          foreach (ToolBoxTab VSTab in VSToolBox.ToolBoxTabs)
          {
              if (VSTab.Name == TabName)
              {
                  MyTab = VSTab;
                  break;
              }
          }      //If tab doesn't exist, creating new one
          if (null == MyTab)
              MyTab = VSToolBox.ToolBoxTabs.Add(TabName);
          MyTab.Activate();
          ToolBoxItem tbi = MyTab.ToolBoxItems.Add("FileBrowser",
              @"MyComponents.FileBrowser, MyTestComps, Version=1.0.0.1, Culture=neutral, PublicKeyToken=2283de3658476795",
              vsToolBoxItemFormat.vsToolBoxItemFormatDotNETComponent);
          DesignTimeEnvironment.Quit();

If i run as administrator its working fine, adding Controls to control library,
but when I try to add the library which is not in GAC its not working. It doesn't through any exception.
Ex:

ToolBoxItem tbi = MyTab.ToolBoxItems.Add("FileBrowser",
  @"C:\MyComponents\MyTestComps.dll",
  vsToolBoxItemFormat.vsToolBoxItemFormatDotNETComponent);