After a long period of search I decide to ask my own question about my problem.
I try to get the value of a Property in Active Directory, but I always get a System.__ComObject.
correspondance += compte.Properties["ENTPersonDateNaissance"][0];
I have tried to use :
Microsoft.VisualBasic.Information.TypeName(compte.Properties["ENTPersonDateNaissance"]
The result is PropertyValueCollection
But I don't know how to get the value?