Hey
Local lnTotal, lnQts, lnQtstotal
lnQts = thisform.txtAjout.value ***it's a numeric
lnTotal = thisform.txtInventaire.value ***it's a numeric and
*** controlesource = produit.inventaire

?????????????
Why Operator it's not good
lnQtstotal = lnQts + lnTotal

replace produit.inventaire with lnQtstotal