Write a formula in an Excel Cell using VBA

Question

I'm trying to use VBA to write a formula into a cell in Excel. My problem is that when I use a semicolon (;) in my formula, I get an error:

Run-time error 1004

My macro is the following :

Sub Jours_ouvres()
    Dim Feuille_Document As String
    Feuille_Document = "DOCUMENT"        
    Application.Worksheets(Feuille_Document).Range("F2").Formula = "=SUM(D2;E2)"    
End Sub