Problems with Paypal IPN standard / checkout

To start with: I'm using Zen Cart 1.3.9h.

I've been using this cart for the past few weeks now and have had several customers email me to say that they were unable to check out with PayPal (It seems all but one customer was from outside the USA). Apparently they received an error page telling them to contact the merchant for assistance.

Going by this thread's recommendation:

http://www.zen-cart.com/forum/showthread.php?p=967909#post967909

I turned off the "Address Override" option. A few of the customers that were having issues before were then able to check out. However, I have received a few more of the same kind of complaints since then.

I know PayPal express is recommended, however I've used IPN standard before with a different version of the cart with no issues. Any assistance on this matter would be appreciated.

It seems all but one customer was from outside the USA
Check with PP as to the countries, as there are some PP rules on other countries

kobra:

Check with PP as to the countries, as there are some PP rules on other countries

The problem though is I have never had this issue until using this version of Zen Cart in question. The same customers who ordered from me in the past cannot do so now.

In the admin note your settings
un install the module and re-install
This may correct the issue

OK, will try that soon. In the meantime I am thinking about just finally switching to Checkout Express.

This morning someone who wasn't able to complete the checkout process yesterday was able to do it today, so I don't know if this is a problem with cookies or what.

Also, where/how do I find my PayPal API signature? I was able to find my API user name and password, but not my signature.

where/how do I find my PayPal API signature?
At PayPal

Yes, I know that, but I couldn't find where in PayPal it was located.

Problem fixed. I updated to Checkout Express and haven't had any issues as of yet.

Thanks for the help!