Can't Manage Bulletins in Carousel - Input String Error Message

When trying to Manage Bulletins in Carousel, we rec'd the following error message: Input string was not in a correct format. We are stuck, can you help?

Error Message TYpe: System.FormatException

THrown At: ASP.list_active_aspx - StringToNumber
Stack Trace: at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)

at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)

at System.Convert.ToInt32(String value)

at TRMS.Web.Carousel.TRMSPage..ctor(String PageID) in d:\src\carousel\Web\Carousel\Classes\PageBuilderToolbox.cs:line 403

at TRMS.Web.Carousel.List_AllActive.groupProperties(String gid) in d:\src\carousel\Web\Carousel\List.Active.aspx.cs:line 1726

at TRMS.Web.Carousel.List_AllActive.Page_Load(Object sender, EventArgs e) in d:\src\carousel\Web\Carousel\List.Active.aspx.cs:line 645