library learning L2

Server Error

Operator '<' is not defined for type 'DBNull' and type 'Integer'.
System.InvalidCastException: Operator '<' is not defined for type 'DBNull' and type 'Integer'.
at Microsoft.VisualBasic.CompilerServices.Operators.CompareObjectLess(Object Left, Object Right, Boolean TextCompare)
at L2.Libraries.LibraryListings.GetAgencyDeliveryBuilding(Int32 AgencyID)
at _libraries_building_aspx.Page_Load(Object sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)