Error message: Specified cast is not valid.

   at Ecommerce.Product.get_UserPrice() in C:\Bone\Ecommerce\src\DBItems\Product\Product.cs:line 582
   at Ecommerce.Product.get_PriceNoVat() in C:\Bone\Ecommerce\src\DBItems\Product\Product.cs:line 677
   at Ecommerce.Product.get_Price() in C:\Bone\Ecommerce\src\DBItems\Product\Product.cs:line 716
   at ASP.tpl_productcategory_view_tpl_ascx.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\inetpub\hellaspharmacy.gr\tpl\ProductCategory.View.tpl.ascx:line 254
   at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
   at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter)
   at System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter)
   at Bone.ActionView.Render(TextWriter w) in C:\Bone\Bone\src\Actions\DBActions\ActionView.cs:line 230
   at Bone.Action.RenderContent(TextWriter w) in C:\Bone\Bone\src\Actions\_Action.cs:line 436
   at Bone.Action.ToString() in C:\Bone\Bone\src\Actions\_Action.cs:line 606
   at Bone.Base.get_Content() in C:\Bone\Bone\src\Classes\Base.cs:line 81
   at ASP.skin_aspx.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\inetpub\hellaspharmacy.gr\skin.aspx:line 306
   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 66
   at Bone.ModalAction.RenderPage(TextWriter w) in C:\Bone\Bone\src\Actions\Modal.cs:line 87
   at Bone.Asp.Render(HtmlTextWriter w) in C:\Bone\Bone\src\Classes\Asp.cs:line 77
   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)