Determine whether a Canvas has been inserted into each page in Word

Currently i have a code which will print OMR Mark on each pages. Basically i insert a Canvas into each page and subsequently an OMR Mark Line Series are inserted into the Canvas.

Recently i found an issue that somehow one of the canvas is placed out of a page and it appears at the previous page instead of the current page.

Below is the code snippet in how i inserted canvas as well as OMR Marks into each page:

' Start Code Snippet
Sub GenerateOMR()
    Dim ShpCan开发者_运维问答vas As Shape
    Dim MaxPages As Integer
    Dim PNo As Integer
    ClearOMR
    MaxPages = Selection.Information(wdNumberOfPagesInDocument)
    For PNo = 1 To MaxPages
        Selection.GoTo What:=wdGoToPage, Which:=wdGoToFirst, Count:=PNo, Name:=""

        Select Case PNo
            Case 1
                Set ShpCanvas = ActiveDocument.Shapes.AddCanvas(0, 0.5, 600, 300)
            Case Else
                Set ShpCanvas = ActiveDocument.Shapes.AddCanvas(0, 0, 600, 300)
        End Select

        ' Add a canvas on each page
        With ShpCanvas
            .Name = "OMR_Canvas_" & CStr(PNo)
            .RelativeHorizontalPosition = wdRelativeHorizontalPositionPage
            .RelativeVerticalPosition = wdRelativeVerticalPositionPage
        End With

        ' Insert a white background rectange and remove the rectangle border line
        With ShpCanvas.CanvasItems.AddShape(msoShapeRectangle, 536, 0, 64, 300)
            .Name = "OMR_WhiteBackground_" & CStr(PNo)
            .Fill.ForeColor.RGB = RGB(255, 255, 255)
            .Line.ForeColor.RGB = RGB(255, 255, 255)
        End With

        PrintOMRPage ShpCanvas, PNo
    Next PNo
End Sub
' End Code Snippet

There is a custom method called PrintOMRPage method which is not relevant here.

My question now, how do i know whether a canvas has been inserted into a page ? Basically i will loop in all the pages and check whether a canvas has been inserted into that page. Apparently i cannot find the correct way.

I have tried to check using ActiveDocument.Shapes(1).Top and validate whether the Top position is a negative value. But apparently the Top position is always measured from the top of each page.

This is the reason you're getting a relative vertical position sometimes: .RelativeVerticalPosition = wdRelativeVerticalPositionPage. Remove it and you'll have a Canvas on each page.