Hi, thanks for the reply. I have activated debugging, and got 2 e-mails, one for Transaction Status Success: and another for Password Failure:. Does this mean my passwords in Zen Cart and WorldPay don't match?
Yeah normally. Either that or your admin > configuration > sessions > recreate sessions could be set to true. This needs to be false. I had this problem a while ago. Are the cencelled transactions returning you to the zen cart?