Éditeur graphique : " Aucune des propriétés sélectionnées n'a d'expression"

I Think , nobody have try to paste an expression and that become a Mess  with After fall down ! 
I think a Short Cut make this situation , but which one ... he seems to wet an enter for his Expression . 
O I find It :  juste à coté de l'oeil , il y a un menu horizontal , et une boite de dialogue : elle propose d'afficher ou de ne pas afficher le modificateur d'expression ...quand je vire ce truc ça remarche . 

The answer is still the same: You need to be specific about what expressions you use on what property and how they interact with keyframes either on the same property or another one.

Mylenium

Bonjour, je sais que le post date un peu mais as tu résolue ton problème ? je viens de rencontrer le même

Without any idea about what expressions you actualyl use we can't tell you much, but the obvious answer would have to be that the code is looking for soemthing external it can't find, be that keyframes or a reference to another property/ effect. You will need to fix that to get correct results.

Mylenium