Value cannot be null.
Parameter name: value
   at System.Enum.IsDefined(Type enumType, Object value)
   at Unsd.Mi.Components.Helpers.StringHelper.ParseEnum[T](String value, T defaultValue) in C:\Development\Unsd\MDG\Components\Helpers\StringHelper.cs:line 115
   at Unsd.Mi.Web.Handlers.ExportHandler.get_ExportType() in d:\Inetpub\unsd\mdg\Handlers\ExportHandler.ashx:line 69
   at Unsd.Mi.Web.Handlers.ExportHandler.ProcessRequest(HttpContext context) in d:\Inetpub\unsd\mdg\Handlers\ExportHandler.ashx:line 176