System.data.constraintexception: failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.

Line 2960:            this.Adapter.SelectCommand = this.CommandCollection[5];
Line 2961:            CDS.ADDJOB_SELECTDataTable dataTable = new CDS.ADDJOB_SELECTDataTable();
Line 2962:            this.Adapter.Fill(dataTable);
Line 2963:            return dataTable;
Line 2964:        }

public partial class AddEducation : System.Web.UI.Page
   {
       SDS.SELECT_ADDEDUDataTable EDT = new SDS.SELECT_ADDEDUDataTable();
       SDSTableAdapters.SELECT_ADDEDUTableAdapter EAdapter = new SDSTableAdapters.SELECT_ADDEDUTableAdapter();