argument not optional in a dll error. Does anyone know why me code is generating this error

Hi
I am using the following code to call functions from a dll

Private Declare Function CreateFile Lib "SynMF.dll" ( _
                                ByVal createfilename As String, _
                                ByVal magic As Long, _
                                ByVal appname As String, _
                                ByVal username As String, _
                                ByVal usercomments As String, _
                                ByVal sourcepath As String, _
                                ByVal sourcename As String, _
                                ByVal firstsourcenumber As Long, _
                                ByVal lastsourcenumber As Long, _
                                ByVal sourcetype As String, _
                                ByVal originx As Double, _
                                ByVal originy As Double, _
                                ByVal originz As Double, _
                                ByVal reversex As Boolean, _
                                ByVal reversey As Boolean, _
                                ByVal reversez As Boolean, _
                                ByVal factorx As Double, _
                                ByVal factory As Double, _
                                ByVal unitsxy As Long, _
                                ByVal factorz As Double, _
                                ByVal unitsz As Long, _
                                ByVal unitsdisplay As Long) As Boolean


When I include the following call

Dim createfilename As String
    createfilename = FileNameBox.Text
   
    Dim magic As Long
    magic = 1
   
    Dim appname As String
    appname = App.Title & " v" & App.Major & "." & App.Minor & "." & App.Revision
   
    Dim username As String
    username = UserNameBox.Text
   
    Dim usercomments As String
    usercomments = UserCommentsBox.Text
   
    Dim sourcepath As String
    sourcepath = SourcePathBox.Text
   
    Dim sourcename As String
    sourcename = SourceNameBox.Text
   
    Dim firstsourcenumber As Long
    firstsourcenumber = FirstSourceBox.Text
   
    Dim lastsourcenumber As Long
    lastsourcenumber = LastSourceBox.Text
   
    Dim sourcetype As String
    sourcetype = FileTypeCombo.Text
   
    Dim originx As Double
    originx = XOriginBox.Text
   
    Dim originy As Double
    originy = YOriginBox.Text
   
    Dim originz As Double
    originz = ZOriginBox.Text
   
    Dim reversex As Boolean
    reversex = XReverseCheck.Value
   
    Dim reversey As Boolean
    reversey = YReverseCheck.Value
   
    Dim reversez As Boolean
    reversez = ZReverseCheck.Value
   
    Dim factorx As Double
    factorx = XYFactorBox.Text
   
    Dim factory As Double
    factory = XYFactorBox.Text
   
    Dim unitsxy As Long
    unitsxy = 3
   
    Dim factorz As Double
    factorz = ZFactorBox.Text
   
    Dim unitsz As Long
    unitsz = 3
   
    Dim unitsdisplay As Long
    unitsdisplay = 2
   
   Dim result As Boolean
'result = CreateFile(createfilename, magic, appname, username, usercomments, sourcepath, sourcename, firstsourcenumber, lastsourcenumber, sourcetype, originx, originy, originz, reversex, reversey, factorx, factory, unitsxy, factorz, unitsz, unitsdisplay)
                             
     result = CreateFile(createfilename, magic, appname, username, usercomments, sourcepath, sourcename, firstsourcenumber, lastsourcenumber, sourcetype, originx, originy, originz, reversex, reversey, factorx, factory, unitsxy, factorz, unitsz, unitsdisplay)
                             
                             
                               
                       
    If result = True Then
        MsgBox "File created"
    Else
        MsgBox "Create FAILED"
    End If


I have tried several configurations with no siccuess anyone any iadea why?