Dani,
I'm getting the same thing. I was getting the transaction failure:
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Transaction Not Completed
We're sorry
Your transaction could not be completed. Either your credit card information or billing address has problems and cannot be processed
Please return to checkout and try again.
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Then I programmed the patch below on my WA_eCart_USPS_PHP.php page and here's what I get:
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80040b1a
Authorization failure. You are not authorized to connect to this server.
UspsCom::DoAuth
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How do I fix this?