ADO or SQL Error ????

I've got some kind of problem. I'm using a VB6 SP3 apps on a SQL Server v7.0 database.

Considering the following Sub:

Private Sub PetitRobert()
Dim strCherche As String
TableSigma.MoveFirst
TableSigma.Find "NomTable = '" & mNomDeTable & "'", , adSearchForward
If Not TableSigma.EOF Then
Dictionnaire.MoveFirst
strCherche = Mid(mNomDuChamp, 1, 5)
Dictionnaire.Find "NomChamp = '" & strCherche & "'", , adSearchForward
If Dictionnaire.EOF Then
Dictionnaire.AddNew
Dictionnaire!NomChamp = strCherche
Dictionnaire!Description = mDescription
Dictionnaire!TypeChamp = mTypeChamp
Dictionnaire!Longueur = mLongueur
Dictionnaire!Decimale = mDecimale
Dictionnaire!EstUneDate = ""
Dictionnaire!NouveauNom = ""
Dictionnaire!NouvelleDescription = ""
Dictionnaire.Update
End If
End If
End Sub

I've got the following error at runtime:

Execution Error '-2147217887 (80040e21)'
Multiple-step operation generated errors.
Check each status value.

The programs stops at the following line:
Dictionnaire!NomChamp = strCherche

What's wrong with my program??? If I try to manually add the data into SQL Server 7.0, no problem whatsoever...

Thanks in advance for any advice or help.

Sincerely, Patrice :-)