Help draw polyline with AddVertexAt vb.net!!!

i just change from vba cad to .net.
it's so difficult.

my code draw polyline then addvextex until escape command
but have problem at red code
if i haven't red code i can't see polyline in screen autocad
if i have it i can not addvextex and error
Attachment 106668

any idea for issue??
+ i want to see polyline in autocad

tks all.

Code:

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Imports AutoCAD

Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.EditorInput
Imports Autodesk.AutoCAD.Runtime
Imports System
Imports System.Windows.Forms
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry


 Public Class THU
        Public Const WidthFactor As Integer = -10
        <CommandMethod("vepl")> _
        Public Sub VEPOLY()


            Dim dblNew(0 To 2) As Double
            Dim lngLastVertex As Long
            Dim varPick As Object
            Dim varPick1 As Object
            Dim varWCS As Object
            Dim dblPoints(3) As Double
            Dim Lineweight As Double
            Dim varpoint, varpoint1 As Object
            Dim i, min, max, NoOfIndices


            Dim doc As Document = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument
            Dim db As Database = doc.Database
            Dim ed As Editor = doc.Editor

            Dim pPtRes As PromptPointResult
            Dim pPtOpts As PromptPointOptions = New PromptPointOptions("")

            On Error Resume Next


            lngLastVertex = 2
            Lineweight = ThisDrawing.ActiveLayer.Lineweight * WidthFactor
         

            '' Prompt for the start point
            pPtOpts.Message = vbLf & "Enter the start point of the line: "
            pPtRes = doc.Editor.GetPoint(pPtOpts)
            Dim ptStart As Point3d = pPtRes.Value
            Dim StarPt As Point2d = New Point2d(pPtRes.Value.X, pPtRes.Value.Y)

            '' Exit if the user presses ESC or cancels the command
            If pPtRes.Status = PromptStatus.Cancel Then Exit Sub

            '' Prompt for the end point
            pPtOpts.Message = vbLf & "\nSelect Next Point: "
            'pPtOpts.SetMessageAndKeywords("\nSelect Next Point: or Exit [Y]", "Yes")
            'pPtOpts.AppendKeywordsToMessage = True
            'pPtOpts.AllowArbitraryInput = True
            pPtOpts.UseBasePoint = True
            pPtOpts.BasePoint = ptStart
            pPtRes = doc.Editor.GetPoint(pPtOpts)

            Dim PtEnd As Point3d = pPtRes.Value
            Dim EndPT As Point2d = New Point2d(pPtRes.Value.X, pPtRes.Value.Y)

            If pPtRes.Status = PromptStatus.Cancel Then Exit Sub

            Using acTrans As Transaction = db.TransactionManager.StartTransaction

                Dim acBlkTbl As BlockTable = acTrans.GetObject(db.BlockTableId, OpenMode.ForRead)
                '' Open the Block table record Model space for write
                Dim acBlkTblRec As BlockTableRecord = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), OpenMode.ForWrite)

                Dim acPoly As Polyline = New Polyline()

                acPoly.SetDatabaseDefaults()
                acPoly.AddVertexAt(0, StarPt, 0, 0, 0)
                acPoly.AddVertexAt(1, EndPT, 0, 0, 0)


                '' Add the new object to the block table record and the transaction
                acBlkTblRec.AppendEntity(acPoly)
                acTrans.AddNewlyCreatedDBObject(acPoly, True)
                acTrans.Commit()
             
                'ed.UpdateScreen()
           
                Do

                    pPtOpts.Message = vbLf & "Enter the Next point of the Polyline: "
                    pPtOpts.UseBasePoint = True
                    pPtOpts.BasePoint = PtEnd
                    pPtRes = doc.Editor.GetPoint(pPtOpts)

                    Dim PtNext As Point2d = New Point2d(pPtRes.Value.X, pPtRes.Value.Y)

                    If pPtRes.Status = PromptStatus.Cancel Then
                        PtEnd = pPtRes.Value
                        Exit Do

                    End If

                    'acPoly.AddVertexAt(acPoly.NumberOfVertices + 1, PtNext, 0, 0, 0)
                    'ed.Regen()
                    acPoly.AddVertexAt(lngLastVertex, PtNext, 0, 0, 0)

                    lngLastVertex = lngLastVertex + 1

                 
                 
                    acBlkTblRec.AppendEntity(acPoly)
                    acTrans.AddNewlyCreatedDBObject(acPoly, True)
                    acTrans.Commit()

                 
                Loop While 1

         
                'AddHandler acPoly.Modified, AddressOf acpolymod
                acTrans.Commit()

            End Using

        End Sub

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Your code have TOO MANY Transaction.Commit() calls.

Whenever Commit() is called, the Transaction is, well, committed and closed. That is why, after the code in red is executed, the code after generates error, because the Transaction is done and closed. You need to remove all the Commit() call in the middle and only keep the very last one. Remember, only either Commit(), or Abort() a Transaction at the very end of the process where the Transaction is needed.

Quote:

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Originally Posted by norman.yuan

Your code have TOO MANY Transaction.Commit() calls.

Whenever Commit() is called, the Transaction is, well, committed and closed. That is why, after the code in red is executed, the code after generates error, because the Transaction is done and closed. You need to remove all the Commit() call in the middle and only keep the very last one. Remember, only either Commit(), or Abort() a Transaction at the very end of the process where the Transaction is needed.

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Correct; Commit() should be called only once within a given Transaction.

However, one can also employ nested Transactions.

Cheers