Как заполнить текстовое поле в winforms с помощью access database in VB.NET при изменении выбора combobox

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я новичок в этом деле. vb.net и я пытаюсь заполнить текстовые поля в моей winform данными из базы данных access о выборе значения в combobox. но это ошибка, которую я получаю.
нет значения для одного или нескольких обязательных параметров.

Что я уже пробовал:

Private Sub employeenamecmbbx_SelectedIndexChanged(sender As Object, e As EventArgs) Handles employeenamecmbbx.SelectedIndexChanged
        Try
            con = New OleDbConnection(cs)
            con.Open()
            Dim ct As String = "select allowances,basicsalary,cashbenefits,vehiclefueldriver,vehiclefuel,fuelonly,vehicleonly," &
                    "accomodationfurnishing,accomodationonly,furnishingonly,sharedaccomodation,marriageresponsibilities,disabled," &
                    "oldage,tier3contribution,lifeinsurance,childeducation,agedependency,trainingcost,ssn,NoOfDependants,nochildren," &
                    "BankName,AccountName,BankBranch,AccountNo," &
                    "from employeeregistration where employeename = ?"
            cmd = New OleDbCommand(ct)
            cmd.Connection = con
            cmd.Parameters.Add(New OleDbParameter("employeename", OleDbType.VarChar, 30))
            cmd.Parameters("employeename").Value = Trim(employeenamecmbbx.Text)
            Console.WriteLine("sql:" & cmd.CommandText)
            rdr = cmd.ExecuteReader()

            If rdr.Read Then
                Allowances.Text = Trim(rdr.GetValue(0).ToString())
                BasicSalary.Text = Trim(rdr.GetString(1))
                CashBenefits.Text = Trim(rdr.GetValue(2).ToString())
                vfd.Text = Trim(rdr.GetValue(2).ToString())
                vf.Text = Trim(rdr.GetValue(3).ToString())
                vonl.Text = Trim(rdr.GetValue(4).ToString())
                feun.Text = Trim(rdr.GetValue(5).ToString())
                accwf.Text = Trim(rdr.GetValue(6).ToString())
                accon.Text = Trim(rdr.GetValue(7).ToString())
                furon.Text = Trim(rdr.GetValue(8).ToString())
                shracc.Text = Trim(rdr.GetValue(9).ToString())
                maresp.Text = Trim(rdr.GetValue(10).ToString())
                disbl.Text = Trim(rdr.GetValue(11).ToString())
                olda.Text = Trim(rdr.GetValue(12).ToString())
                t3c.Text = Trim(rdr.GetValue(13).ToString())
                lifins.Text = Trim(rdr.GetValue(14).ToString())
                chedu.Text = Trim(rdr.GetValue(15).ToString())
                agdep.Text = Trim(rdr.GetValue(16).ToString())
                trncst.Text = Trim(rdr.GetValue(17).ToString())
                ssno.Text = Trim(rdr.GetValue(18).ToString())
                Nodependents.Text = Trim(rdr.GetValue(19).ToString())
                NoChildren.Text = Trim(rdr.GetValue(20).ToString())
                bntnmtxbx.Text = Trim(rdr.GetValue(21).ToString())
                actntxbx.Text = Trim(rdr.GetValue(22).ToString())
                brncnamtxbx.Text = Trim(rdr.GetValue(23).ToString())
                accnmtxbx.Text = Trim(rdr.GetValue(24).ToString())
            End If
            If Not rdr Is Nothing Then
                rdr.Close()
            End If

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