DataGridView, поиск значения в таблице

Private Sub btnFind_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFind.Click
For i = 0 To СтудентDataGridView.ColumnCount - 1
For j = 0 To СтудентDataGridView.RowCount - 1
СтудентDataGridView.Item(i, j).Style.BackColor = Color.White
СтудентDataGridView.Item(i, j).Style.ForeColor = Color.Black
Next j
Next i
For i = 0 To СтудентDataGridView.ColumnCount - 1
For j = 0 To СтудентDataGridView.RowCount - 1
If InStr(СтудентDataGridView.Item(i, j).Value, txtFind.Text) Then
СтудентDataGridView.Item(i, j).Style.BackColor = Color.AliceBlue
СтудентDataGridView.Item(i, j).Style.ForeColor = Color.Blue
End If
Next j
Next i
End Sub

' livesearch
        Private Sub TextBox2_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles TextBox2.TextChanged
            Dim a As Boolean = False
            Dim Row As DataGridViewRow
            Dim str_find As String = TextBox2.Text
            For Each Row In DataGridView1.Rows
                If (Row.Cells(1).Value.ToString().ToLower.Contains(str_find.ToLower)) Then
                    DataGridView1.CurrentCell = Row.Cells(1)
                    DataGridView1.Rows(Row.Index).Selected = True
                    a = True
                End If
            Next
            If a = False Then
                'MsgBox("Материал " & str_find & " не найден", 32, "Поиск")
            End If
        End Sub

If (Row.Cells(1).Value.ToString().ToLower.Contains(str_find.ToLower)) Then

For i = 0 To СтудентDataGridView.ColumnCount - 1
For j = 0 To СтудентDataGridView.RowCount - 1
If InStr(СтудентDataGridView.Item(i, j).Value