Error message: Specified cast is not valid.

Url: http://aequip.gr/skin.aspx?lang=el&itemtype=ProductCategory&itemid=00990CB6&action=view&00002328=055D4B0C‡055D4AD3‡055D4A8D‡055D4ADA‡055D4AB0‡055D4B49‡055D4A9B‡055D4B43‡055D4AA5‡055D4AC6&splitter_products_offset=72

Message: Specified cast is not valid.

   at ContentBuilder.CONTENTBUILDER.get_IsSliderEnabled() in C:\Bone\ContentBuilder\ContentBuilder.cs:line 41
   at ContentBuilder.ContentBuilderPlugin.get_Head() in C:\Bone\ContentBuilder\ContentBuilderPlugin.cs:line 56
   at Bone.Base.get_PluginExtraHeads() in C:\Bone\Bone\src\Classes\Base.cs:line 307
   at Bone.Base.get_Head() in C:\Bone\Bone\src\Classes\Base.cs:line 501
   at ASP.skin_aspx.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\inetpub\wwwroot\skin.aspx:line 42
   at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
   at System.Web.UI.Page.Render(HtmlTextWriter writer)
   at Bone.Asp.RenderSkin(TextWriter w) in C:\Bone\Bone\src\Classes\Asp.cs:line 71
   at Bone.ModalAction.RenderPage(TextWriter w) in C:\Bone\Bone\src\Actions\Modal.cs:line 81
   at Bone.Asp.Render(HtmlTextWriter w) in C:\Bone\Bone\src\Classes\Asp.cs:line 82
   at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter)
   at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter)
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)