Macro not working

[cafc_fuller]

Hello,

I have a sheet when a button is clicked to run the macro below, however I get the error
"Cannot run the macro 'Despatch.xlsm"Tracking'. The macro may not be available in this workbook or all macros may be disabled."

If i run the macro in VBA it works fine? Macros are enabelled - does anyone know why this is?
Also is there a way when emailing the body of an email to keep the format of text etc?
Last point for the to: i want the value to be that of Cell B12 (this is where the email address is)

Thanks
Darren

Sub Mail_Sheet_Outlook_Body()

    Dim rng As Range
    Dim OutApp As Object
    Dim OutMail As Object
    
    With Application
        .EnableEvents = False
        .ScreenUpdating = False
    End With

    Set rng = Nothing
    Set rng = Sheets("Despatch").UsedRange

    Set OutApp = CreateObject("Outlook.Application")
    Set OutMail = OutApp.CreateItem(0)

    On Error Resume Next
    With OutMail
        .To = ""
        .CC = ""
        .BCC = ""
        .Subject = "Despatch"
        .HTMLBody = RangetoHTML(rng)
        .display
    End With
    On Error GoTo 0

    With Application
        .EnableEvents = True
        .ScreenUpdating = True
    End With

    Set OutMail = Nothing
    Set OutApp = Nothing
End Sub


Function RangetoHTML(rng As Range)
    Dim fso As Object
    Dim ts As Object
    Dim TempFile As String
    Dim TempWB As Workbook

    TempFile = Environ$("temp") & "\" & Format(Now, "dd-mm-yy h-mm-ss") & ".htm"

    'Copy the range and create a new workbook to past the data in
    rng.Copy
    Set TempWB = Workbooks.Add(1)
    With TempWB.Sheets(1)
        .Cells(1).PasteSpecial Paste:=8
        .Cells(1).PasteSpecial xlPasteValues, , False, False
        .Cells(1).PasteSpecial xlPasteFormats, , False, False
        .Cells(1).Select
        Application.CutCopyMode = False
        On Error Resume Next
        .DrawingObjects.Visible = True
        .DrawingObjects.Delete
        On Error GoTo 0
    End With

    'Publish the sheet to a htm file
    With TempWB.PublishObjects.Add( _
         SourceType:=xlSourceRange, _
         Filename:=TempFile, _
         Sheet:=TempWB.Sheets(1).Name, _
         Source:=TempWB.Sheets(1).UsedRange.Address, _
         HtmlType:=xlHtmlStatic)
        .Publish (True)
    End With

    'Read all data from the htm file into RangetoHTML
    Set fso = CreateObject("Scripting.FileSystemObject")
    Set ts = fso.GetFile(TempFile).OpenAsTextStream(1, -2)
    RangetoHTML = ts.readall
    ts.Close
    RangetoHTML = Replace(RangetoHTML, "align=center x:publishsource=", _
                          "align=left x:publishsource=")

    'Close TempWB
    TempWB.Close savechanges:=False

    'Delete the htm file we used in this function
    Kill TempFile

    Set ts = Nothing
    Set fso = Nothing
    Set TempWB = Nothing
End Function