@Arturo83, ajoutez "application.volatile" au début de votre fonction, changer le couleur n'est pas suffisant pour recalculer tout.
Function Ampl(Plage As Range, Ligne As Long) As Double
Dim i As Long, DerCol As Long, deb As Double, fin As Double
Application.volatile
DerCol = Range("ZZ8").End(xlToLeft).Column For i = 6 To DerCol
etc