'Run time error 1101.Argument value not valid.

Hello,

On one PC with Project Pro 2007, this VBA excerpt below works fine. 

On two others PC with Project Pro 2010, I get an error on the Set Statement:  'Run time error1101. Argument value not valid.

Any idea ?

Thanks

Dim oRes As Resource
Dim Asg As Assignment 'Task Assignment
Dim Res_Ass As Assignment 'Resource Assignment
Dim oTache As Task
Dim SousProj As Object

.../...

For Each oTache In ActiveProject.Subprojects(I).SourceProject.Tasks

        If Not oTache Is Nothing Then
            oTache.Text5 = ActiveProject.Subprojects(I).SourceProject.BuiltinDocumentProperties("Comments")
            For Each Asg In oTache.Assignments
                Asg.Text5 = ActiveProject.Subprojects(I).SourceProject.BuiltinDocumentProperties("Comments")

                Asg.Text4 = ActiveProject.Subprojects(I).SourceProject.BuiltinDocumentProperties("Keywords")

                Set oRes = ActiveProject.Resources(Asg.ResourceID)  'Run time error 1101.Argument value not valid.

Erreur d'exécution 1101 Valeur d'argument non valide