VBA TO vb.NET

Hi i am facing problem while extracting utility ratio from staad to excel, it was working well with VBA  but in VB.net its giving error

please check the below code and suggest me suitable solution.Thank you

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click

''CREATING EXCEL FILE
Dim xlApp As Excel.Application = New Microsoft.Office.Interop.Excel.Application()

Dim xlWorkBook As Excel.Workbook
Dim xlWorkSheet As Excel.Worksheet
Dim misValue As Object = System.Reflection.Missing.Value

Dim objOpenSTAAD As Object

Dim lBeamCnt As Long
Dim BeamNumberArray(-1) As Long


Dim mem As Long
Dim pdRatio As Double
Dim sBeamMaterialName As String


Dim lBeamSectionName As String

xlWorkBook = xlApp.Workbooks.Add(misValue)
xlWorkSheet = xlWorkBook.Sheets("sheet1")


'' EXTRACTING ASPECT RATIO

xlWorkSheet.Range("A4:e10010").ClearContents()
xlWorkSheet.Sheets("Sheet1").Select


objOpenSTAAD = GetObject(, "StaadPro.OpenSTAAD")

lBeamCnt = objOpenSTAAD.Geometry.GetMemberCount


objOpenSTAAD.Output.GetMemberSteelDesignRatio(mem, pdRatio)


ReDim BeamNumberArray(0 To (lBeamCnt - 1)) As Long
objOpenSTAAD.Geometry.GetBeamList(BeamNumberArray)
For I = 1 To lBeamCnt
xlWorkSheet.Sheets("Sheet1").Cells(I + 3, 1) = BeamNumberArray(I - 1)
mem = xlWorkSheet.Sheets("Sheet1").Cells(I + 3, 1).Value
objOpenSTAAD.Output.GetMemberSteelDesignRatio(mem, pdRatio)
xlWorkSheet.Sheets("Sheet1").Cells(I + 3, 4) = pdRatio
sBeamMaterialName = objOpenSTAAD.Property.GetBeamMaterialName(mem)
lBeamSectionName = objOpenSTAAD.Property.GetBeamSectionName(mem)
xlWorkSheet.Sheets("Sheet1").Cells(I + 3, 2) = sBeamMaterialName
xlWorkSheet.Sheets("Sheet1").Cells(I + 3, 3) = lBeamSectionName

Next I

End Sub