Get Selection with Keyword Options

Hi everyone;

I am trying to write a plugin which asks me to select some lines and while doing it asks for a keyword to show some application forms. Here is the code I have written so far:

Public Class Test

Dim keyword as string = nothing

Public Sub VOLengthtoBlock()
       Dim doc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
       Dim db As Database = doc.Database
       Dim ed As Editor = doc.Editor

       tlinelen = 0
       lenmultiplier = frmTools.TextBox1.Text

       Try

           Dim tr As Transaction = db.TransactionManager.StartTransaction()
           Using tr

               'Select Objects
               Dim opt As New PromptSelectionOptions()

               opt.SetKeywords("[Options/Scale]", "Options Scale")
               opt.MessageForAdding = vbLf & "Select objects or " & opt.Keywords.GetDisplayString(True)
               AddHandler opt.KeywordInput, AddressOf onKeywordInput

               Select Case keyword

                   Case "Options"
                       frmTools.ShowDialog()
                   Case "Scale"
                       frmScale.ShowDialog()

               End Select

               Dim selres As PromptSelectionResult = Nothing
               selres = ed.GetSelection(opt)

               If selres.Status <> PromptStatus.OK Then
                   Return
               End If

               Dim selset As SelectionSet = selres.Value

               'Get Line Lengths
               If selres.Status = PromptStatus.OK Then

                   For Each selobj As SelectedObject In selset

                       Dim sent As Entity = DirectCast(tr.GetObject(selobj.ObjectId, OpenMode.ForWrite), Entity)

                       If TypeOf sent Is Line Then

                           Dim curline As Line = TryCast(sent, Line)

                           tlinelen = tlinelen + curline.Length

                       ElseIf TypeOf sent Is Polyline Then

                           Dim curline As Polyline = TryCast(sent, Polyline)

                           tlinelen = tlinelen + curline.Length

                       End If

                   Next

                   tlinelen = CInt(tlinelen * lenmultiplier)
                   bBlockLength = True

                   VOMEditBlock()

                   bBlockLength = False

               End If
               tr.Commit()
           End Using

       Catch ex As Autodesk.AutoCAD.Runtime.Exception
           MsgBox(ex.ToString)
       End Try
   End Sub


   Private Sub onKeywordInput(sender As Object, e As SelectionTextInputEventArgs)
       Me.keyword = e.Input
   End Sub

End class

It does not show my form until I exit from the sub and call it again. When i call it again, it just shows the form. I couldn't find the error. Please help.