139 paypal express check out final check out page "blank"

[mc12345678]

Thank you for reply,
Sometimes USPS can show international shipping rate( this is what we need in the future),
but can not pass the shipping rate to PayPal,
The domestic shipping rate cannot show at all, sometimes blank,
and when I add definition zones on USPS, the shipping estimator gone!
I try to find log file, but I did not find it.( I am new)

So, assuming when you said you are new, that you have then installed version 1.5.1 or higher of Zen Cart. Error log files (if permissions to the directory allow writing) are in the stores directory, sub-folder logs. Error logs are typically created in ZC when a blank page is displayed. The host may have also captured one or more errors in their log files (different path setup by web host).

I'm also guessing (assuming) that you have the latest USPS module installed (July 30th J5 I think was the version). There have been some changes in the process that have effected some having the older USPS version(s) installed.

The shipping rate should eventually be a part of the final price paid by the customer. What version of PayPal processing is being used? (Might make a difference)