Hook to modify price at POS

Hello

I would like to modify the price automaticaly at the pos when quantity is modified on the POS To do that i would like to use Hooks and VB6

i do a little VB to test

the hook i use is REFRESHDISPLAY

the vb program is

Public Function Process(objSession As Object) As Boolean

Dim entryCount, Ikey As Integer Ikey = objSession.Transaction.Entries.Count

For entryCount = 1 To Ikey LItemID = objSession.Transaction.Entries.Element(entryCount).Item.ID objSession.Transaction.Entries.Element(entryCount).SetPrice(33)

msgbox "OK" next Process = True End function

The problem is that the fist time i go through he doesn't modify the price on the pos but the red flash is coming up. If i enter an other quantity then the price is updated to 33

I have to go through twice

Thanks for your help

Best regards Didier