A relation already exist for these child columns

I am trying to create a relation between one parent table and three child tables.  When I enter the code that I think is correct to build these realtions, I get "A relation already exist for these child columns".  I have commented out some code that I thought was creating the problem but the problem still exist.  Any insight to this error would be greatly appreciate.

Thanks
Kenny

Here is the code:


SqlDataAdapter sqlDA = CreateProviderAdapter();
        SqlDataAdapter sqlDAphyins = CreateProviderInsAdapter();
        SqlDataAdapter sqlDAphyspecial = CreateProviderSpecialAdapter();
        SqlDataAdapter sqlDAphyspecialproc = CreateProviderSpecialProcAdapter();
        HDSDataSet.Clear();

       sqlDA.FillSchema(HDSDataSet, SchemaType.Source);

       


        sqlDA.Fill(HDSDataSet, "PROVIDER");
        sqlDAphyins.Fill(HDSDataSet, "PHYS_INS_CARRIER");
        sqlDAphyspecial.Fill(HDSDataSet, "PHYS_SPECIALTIES");
        sqlDAphyspecialproc.Fill(HDSDataSet, "SPECIAL_PROCEDURES");

        errormessage.Text = ProviderSearch;
        errormessage2.Text = SearchProviderIns;
        errormessage3.Text = SearchProvSpecialty;

       // DataColumn[] keys = new DataColumn[1];
       // keys[0] = HDSDataSet.Tables["PROVIDER"].Columns["PHYSICIAN_NPI"];
      //  HDSDataSet.Tables["PROVIDER"].PrimaryKey = keys;

       // DataColumn[] key1 = new DataColumn[1];
        // key1[0] = HDSDataSet.Tables["PHYS_INS_CARRIER"].Columns["PHYSICIAN_NPI"];
        // HDSDataSet.Tables["PHYS_INS_CARRIER"].PrimaryKey = key1;

        //  DataColumn[] key2 = new DataColumn[1];
        //  key2[0] = HDSDataSet.Tables["PHYS_SPECIALTIES"].Columns["PHYSICIAN_NPI"];
        //  HDSDataSet.Tables["PHYS_SPECIALTIES"].PrimaryKey = key2;

        //  DataColumn[] key3 = new DataColumn[1];
        //  key3[0] = HDSDataSet.Tables["SPECIAL_PROCEDURES"].Columns["PHYSICIAN_NPI"];
        //  HDSDataSet.Tables["SPECIAL_PROCEDURES"].PrimaryKey = key3;


        HDSDataSet.Relations.Add("InsuranceRelation", HDSDataSet.Tables["Provider"].Columns["PHYSICIAN_NPI"], HDSDataSet.Tables["PHYS_INS_CARRIER"].Columns["PHYSICIAN_NPI"]);-------------<<<<<<<< ERROR OCCURS ON THIS LINE
        HDSDataSet.Relations.Add("SpecialityRelation", HDSDataSet.Tables["Provider"].Columns["PHYSICIAN_NPI"], HDSDataSet.Tables["PHYS_SPECIALTIES"].Columns["PHYSICIAN_NPI"]);
        HDSDataSet.Relations.Add("SpecialProcRelation", HDSDataSet.Tables["Provider"].Columns["PHYSICIAN_NPI"], HDSDataSet.Tables["SPECIAL_PROCEDURES"].Columns["PHYSICIAN_NPI"]);

     
        Cache["HDS"] = HDSDataSet;

    }

    protected SqlDataAdapter CreateProviderAdapter()
    {
        SqlConnection conn = new SqlConnection(ConnString);
        SqlCommand cmd = new SqlCommand(ProviderSearch, conn);
       
        cmd.Parameters.Add(new SqlParameter("@SearchCity", txtSearchCity.Text));
        cmd.Parameters.Add(new SqlParameter("@SearchState", txtSearchState.Text));
        cmd.Parameters.Add(new SqlParameter("@SearchZip", txtSearchZip.Text));

        SqlDataAdapter sqlDA = new SqlDataAdapter(cmd);
        return sqlDA;
    }

    protected SqlDataAdapter CreateProviderInsAdapter()
    {
        SqlConnection connProvIns = new SqlConnection(ConnString);
        SqlCommand cmd = new SqlCommand(SearchProviderIns, connProvIns);
       
        cmd.Parameters.Add(new SqlParameter("@SearchInsur", txtSearchInsur.Text));


        SqlDataAdapter sqlDAphyins = new SqlDataAdapter(cmd);
        return sqlDAphyins;
    }

    protected SqlDataAdapter CreateProviderSpecialAdapter()
    {
        SqlConnection connPhysSpecial = new SqlConnection(ConnString);
        SqlCommand cmd = new SqlCommand(SearchProvSpecialty, connPhysSpecial);
        cmd.Parameters.Add(new SqlParameter("@SearchSpecialty", txtSearchSpecial.Text));
        SqlDataAdapter sqlDAphyspecial = new SqlDataAdapter(cmd);
        return sqlDAphyspecial;
    }

    protected SqlDataAdapter CreateProviderSpecialProcAdapter()
    {
        SqlConnection connPhysSpecialProc = new SqlConnection(ConnString);
        SqlCommand cmd = new SqlCommand(SearchProvSpecialtyProc, connPhysSpecialProc);
        cmd.Parameters.Add(new SqlParameter("@SearchSpecialtyProc", txtSearchSpecialProcCode.Text));
        SqlDataAdapter sqlDAphyspecialproc = new SqlDataAdapter(cmd);
        return sqlDAphyspecialproc;
    }


    private String ConnString
    {
        get
        {
            //HDS ConnectionString comes from the Web.Config
            return ConfigurationManager.ConnectionStrings["Chart RelayConnectionString"].ConnectionString;

        }
    }

    private String ProviderSearch
    {
        get
        {
            String srchCmd = "Select PHYSICIAN_NPI, LAST_NAME, FIRST_NAME, ADDRESS_1, CITY, STATE, PHONE from Provider";

            if (txtSearchCity.Text != "")
                srchCmd += " where city = @SearchCity";

            if(txtSearchState.Text != "")
                srchCmd += " and STATE = @SearchState";

            if (txtSearchZip.Text != "")
                srchCmd += " and ZIP = @SearchZip";


            srchCmd += " ORDER BY WEIGHT";
               
            return srchCmd;

        }
    }

    private String SearchProviderIns
    {
        get
        {
            String srchCmd = "Select * from PHYS_INS_CARRIER";

            if (txtSearchInsur.Text != "")
                srchCmd += " where INSURANCE_CARRIER_NAME = @SearchInsur";
           
            return srchCmd;

        }
    }

    private String SearchProvSpecialty
    {
        get
        {
            String srchCmd = "Select * from PHYS_SPECIALITIES";

            if(txtSearchSpecial.Text != "")
            srchCmd += " where DESCRIPTION = @SearchSpecialty";

            return srchCmd;

        }
    }

    private String SearchProvSpecialtyProc
    {
        get
        {
            String srchCmd = "Select * from SPECIAL_PROCEDURES";

            if (txtSearchSpecialProcCode.Text != "")
                srchCmd += " where CPT = @SearchSpecialtyProc";

            if (txtSearchSpecialProcDesc.Text != "")
                srchCmd += " where DESCRIPTION = @SearchSpecialtyProc";

            return srchCmd;

        }
    }