I'm opening an Excel file and using the header row to fill a list box.

The code below works until I turn on the project setting to disallow late binding. Then line in bold is producing a problem. Is there an easier way to do what I want without having to turn off the late binding warning/error?

Code:
        Dim strList As String = ""
        Dim i As Integer = 1
        Dim oSht As New Excel.Worksheet
        Dim oWB As Excel.Workbook

        Try
            'Create an Excel instance.
            oApp = New Excel.Application
            oWB = oApp.Workbooks.Open("c:\temp\test.xls")
            oSht = CType(oWB.ActiveSheet, Excel.Worksheet)

            Do
                strList = CType(oSht.Cells(1, i).value, String)
                If strList = "" Then
                    Exit Do
                End If
                lstAllVars.Items.Add(strList)
                i = i + 1
            Loop While strList <> ""

            'close and clean up resources
            oApp.Quit()
            oApp = Nothing
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString)
        End Try