Try adding Server validation to the checkout form in order make sure the entire form is being filled in.
see the following thread for details on using server validation with the eCart checkout form:
i have the validations in and working fine.
i have checked and when an address is submited on our checkout page it DOES pass to paypal but their address only appears when you choose "dont have a pay pal account" where you can pay directly from your credit card section. their address is shown there. but the address WILL NOT show when you choose to login to paypal to pay. would that be a problem with the ecart5? or would that be a problem with paypal not having their members address on record show on the print out?.