Message Box Issue

Hey guys,

I have the following piece of code:

Public Sub ELITE_POBF()
    Dim Wst As Worksheet, R As Range
    
    Workbooks.Open ("C:\Users\Public\POBF\POBF.xls")
    
    Set Wst = Workbooks("POBF").Worksheets("Elite Extrusion Die") 'change this to the right sheet in the right workbook
    
    Set R = Wst.Columns("A:A").Find(What:=ThisWorkbook.Sheets("Delivery Note").Range("C18"), LookIn:=xlValues, LookAt:=xlWhole)
    If Not R Is Nothing Then
        MsgBox "You Should Have " & R.Offset(0, 1) - Application.WorksheetFunction.Sum(ThisWorkbook.Sheets("Delivery Note").Range("A21:A44")) & " Pieces Left On The Purchase Order, Is This Correct?"
    ElseIf MsgBox("The Order Number You Have Entered Has Been Entered Incorrectly Or Has Not Been Booked In, Please Press No And Follow This Up Before Continuing.", vbYesNo + vbDefaultButton2) = vbYes Then
        'whatever your 'continue' code is
    End If
End Sub

Now, for some reason, the message box only comes up with a Yes No option for the "ElseIf" statement and for the "If" statement above it, the only option for the user to click is "OK", however I would like this to be the other way round, how can I do this?

Any ideas will be greatly appreciated.

Jamer