Specified Cast is not Valid

[Smokeywade]

What I'm trying to do in a listview is calculate the time now from a time in the table and place that result into a column on the grid for each record.
I was able to do this great using a datagrid, I'm exploring into the listview world and I cant seem to figure out how to do this...here is my code

Function fncDaysOpen()
        
        Dim row As Integer
              Try
            For row = 0 To Mydataset3.Tables(0).Rows.Count - 1
  
'Convert DateTime String              
                Dim order_date As String
                order_date = lstGrid.Items(row).SubItems(2).Text
                Dim conv As DateTime
                conv = System.Convert.ToDateTime(order_date)

                Dim d1 As DateTime = conv
                Dim d2 As DateTime = System.DateTime.Today

                Dim subtract, absday
                subtract = 0
                Select Case DatePart("w", d1)
                    Case 1
                        subtract = subtract + 1
                    Case 7
                        subtract = subtract + 2
                End Select

                Select Case DatePart("w", d2)
                    Case 1
                        subtract = subtract + 2
                    Case 7
                        subtract = subtract + 1
                End Select
                absday = DateDiff("d", d1, d2) - 1

                fncDaysOpen = absday - CInt(2 * (absday \ 7))

               'I get My Error Right Here - when placing results for each rec.                  
 lstGrid.Items(row).SubItems(7).Text = fncDaysOpen

                           Next row
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
    End Function<b></b>

Thanks For Any Help