error system.argumentexception: datagridviewcomboboxCell value not Valid

[Keerti]

I have a DGV(unbound) with many Columns and one of the Column is ComboBoxColumn. I want to add Items in it whenever user enters in the First column. This I am able to do on CellValueChange Event . i.e. if Cell Value of Index 1 changes then 3related Items (say A,B &C) are added to combo of Comboboxcolumn and item at 0 Index (A) is set as default selection, and before adding these items I am clearing the Combobox.
Please note that Items to be added in combo may be different in different rows, e.g. maybe in 2nd Row Combo 3related Items may be say A,D &F.
After adding some data , if User want to EDIT the selection done in Combobox in any row then user will directly enter in that Combobox column. So to take care of it I am taking help of CellBeginEdit Event to Load the 3 Items related to Column1 Item of that Particular Row. Loading is successful.
Now issue comes if user changes the selection in combobox by directly entering in the combobox Column, it gives error
“system.argumentexception: datagridviewcomboboxCell value not Valid”
My Best guess is it due to different Itemset of combo in different rows.
What may be the solution, any suggestions?

Public Class Test2
         Dim CBItmUnit As New DataGridViewComboBoxColumn
    Const ClmnCntDGV2 As Integer = 5
    Dim UnitArrayList As New ArrayList
    Dim V_SalesVoucher As New DataTable

    Private Sub Test2_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        With V_SalesVoucher.Columns
            .Add("1", GetType(Integer))
            .Add("2", GetType(String))
            .Add("3", GetType(Integer))
            .Add("4", GetType(String))
            .Add("5", GetType(Integer))

        End With
        With V_SalesVoucher.Rows
            .Add(1, "Itm1", 10, "Box", 100)
            .Add(2, "Itm2", 20, "Box", 110)
        End With

        With DGVItemDetail
            Try
                '       Set AutoGenerateColumns False
                .AutoGenerateColumns = False
                '       Set Visible Columns Count
                .ColumnCount = ClmnCntDGV2
                '       Add Columns
                .DataSource = V_SalesVoucher
                ' // Set Column Header Text and Width
                .RowHeadersVisible = True

                .Columns(0).HeaderText = "S.No." : .Columns(0).Width = 70 : .Columns(0).ReadOnly = True : .Columns(0).DataPropertyName = "1"
                .Columns(1).HeaderText = "Item" : .Columns(1).AutoSizeMode = System.Windows.Forms.DataGridViewAutoSizeColumnMode.Fill : .Columns(1).DataPropertyName = "2"                                '
                .Columns(2).HeaderText = "Qty" : .Columns(2).Width = 90 : .Columns(2).DataPropertyName = "3"
                .Columns(3).HeaderText = "List Price" : .Columns(3).Width = 100 : .Columns(3).DataPropertyName = "4"
                .Columns(4).HeaderText = "Unit" : .Columns(4).Width = 100 : .Columns(4).Visible = False : .Columns(4).DataPropertyName = "5"



                .Columns.Insert(5, CBItmUnit)
                CBItmUnitSetting()

            Catch ex As Exception
                MsgBox(ex.ToString)
            End Try

            .ReadOnly = False
        End With

    End Sub

    Private Sub CBItmUnitSetting()

        With CBItmUnit
            .Name = "CBItmUnit"
            .DisplayStyle = System.Windows.Forms.DataGridViewComboBoxDisplayStyle.ComboBox
            .DisplayStyleForCurrentCellOnly = True
            .DataSource = UnitArrayList
            .HeaderText = "Unit"
            .Width = 90
        End With

        For n As Integer = 0 To DGVItemDetail.Rows.Count - 1
            If DGVItemDetail(4, n).Value IsNot Nothing Then
                UnitArrayList.Add(DGVItemDetail(4, n).Value)
                DGVItemDetail(5, n).Value = DGVItemDetail(4, n).Value
            End If
        Next

    End Sub

    Private Sub DGVItemDetail_CellBeginEdit(sender As Object, e As DataGridViewCellCancelEventArgs) Handles DGVItemDetail.CellBeginEdit
        If DGVItemDetail.CurrentCell.ColumnIndex = 5 Then
            Dim nrow As Integer = DGVItemDetail.CurrentCell.RowIndex
            
            If nrow = 0 Then                                                   'Findrows.Count > 0 Then
                UnitArrayList.Clear()
                UnitArrayList.Add("Box")                           '(Findrows(0)("sItmMainUnit").ToString)
                UnitArrayList.Add("Pc")                                 '(Findrows(0)("sItmAltUnit").ToString)
                UnitArrayList.Add("Case")                                   '(Findrows(0)("sItmPackUnit").ToString)
                CBItmUnit.DataSource = UnitArrayList
                SendKeys.Send("{F4}")
            ElseIf nrow = 1 Then
                UnitArrayList.Clear()
                UnitArrayList.Add("Box")                           '(Findrows(0)("sItmMainUnit").ToString)
                UnitArrayList.Add("Pack")                                 '(Findrows(0)("sItmAltUnit").ToString)
                UnitArrayList.Add("XXX")                                   '(Findrows(0)("sItmPackUnit").ToString)
                CBItmUnit.DataSource = UnitArrayList
                SendKeys.Send("{F4}")
            End If

        End If
    End Sub



End Class