Why would DataGridView.ColumnCount be valid on one form and be 0 when referenced from

[sjsommer]

I use the following code to populate and format a DataGridView on one form:

        Dim qryString As String = "SELECT tblBasicData.DataField1 AS Item, tblBasicData.DataField2 AS Hazard, " &
            "tblHIDChecklist.[Exists (Y/N)] AS [Exists], tblHIDChecklist.Description, tblBasicData.DataOrder " &
            "FROM tblBasicData INNER JOIN tblHIDChecklist ON tblBasicData.BasicDataUID = tblHIDChecklist.BasicDataUID " &
            "WHERE (((tblHIDChecklist.Export)=True)) " &
            "UNION " &
            "SELECT tblHIDDetail.HIDDetailUID AS Item, tblHIDDetail.Description AS Hazard, " &
            "tblHIDDetail.Quantity AS [Exists], tblHIDDetail.Units AS Descripition, tblBasicData.DataOrder " &
            "FROM (tblBasicData INNER JOIN tblHIDChecklist ON tblBasicData.BasicDataUID = tblHIDChecklist.BasicDataUID) " &
            "INNER JOIN tblHIDDetail ON tblHIDChecklist.HIDChecklistUID = tblHIDDetail.HIDChecklistUID " &
            "ORDER BY DataOrder;"
 
        ConnDB()
        Dim cmd As New System.Data.OleDb.OleDbCommand(qryString, Conn)
        dapDGV.SelectCommand = New OleDb.OleDbCommand(qryString, Conn)
 
        Dim cmb As New System.Data.OleDb.OleDbCommandBuilder(dapDGV)
        dapDGV.Fill(dasDGV)
        dgvExport.DataSource = dasDGV.Tables(0)
        Conn.Close()
        dgvExport.Columns("DataOrder").Visible = False
        If dasDGV.Tables(0).Rows.Count > 0 Then
            'Sequence through dataset and remove UIDs from any Detail records.
            'Convert any -1 or 0s to blanks in all checklist records
            For iRow As Integer = 0 To dgvExport.Rows.Count - 1
                If Len(dgvExport.Rows(iRow).Cells("Item").Value) = 36 Then
                    dgvExport.Rows(iRow).Cells("Item").Value = ""
                End If
                If dgvExport.Rows(iRow).Cells("Exists").Value = -1 Then
                    dgvExport.Rows(iRow).Cells("Exists").Value = ""
                ElseIf dgvExport.Rows(iRow).Cells("Exists").Value = 0 Then
                    dgvExport.Rows(iRow).Cells("Exists").Value = ""
                End If
            Next
        Else
            MsgBox("No records have been identified for export.")
        End If
 
        MsgBox(dgvExport.ColumnCount)
End Sub

I open a 2nd form using Form2.Show() where the first step is :

MsgBox(frmHazCatExport.dgvExport.ColumnCount)

When I test the routine, the first form shows data and the msgbox displays that there are 5 columns in the datagridview. However, when I open the 2nd form the msgbox displays that the columncount is 0. I am running this test because I'm trying to access columns in the datagridview but I am only able to access the form and the DGV itself. Anything beyond that (i.e., rows, columns) generates an error I assume because form2 thinks there are 0 columns in the DGV on the first form. The error generated is "Reference to a non-shared member requires an object reference." I'm confused. How can the form1 tell me there are 5 columns and the "next" step tell me there are 0 columns?

[Frinavale]

When you open form2 do you have a proper reference to the instantiated form1?

Is your Grid View public?

Did you consider adding a property "column count" in Form 1 that you can access in Form 2?