Try sending a request "manually" by typing the following URL into your browser:

If the USPS server doesn't send you a valid response to this string, then your problem is not with the Ubercart code.

What version of Ubercart, uc_usps, & PHP are you using? There have been a lot of changes to the shipping modules recently. It's a bit unclear exactly what minimum version of PHP is required, but if you're using PHP 4.something there's a chance that this is the problem.

In Firebug, you're looking at the response from "POST http://example.com/cart/checkout/shipping/quote" ? If you send invalid info to the USPS server, you should at least get back an error. If you don't see any response I would venture to guess the request was never sent. Before you go any further I would switch to a default theme to ensure jQuery etc. is getting included on your pages. You can then stick in these print statements, one right before the call to drupal_http_request() and one right after (in uc_usps.module, function uc_usps_quote()):
drupal_set_message('<pre>'. htmlentities($request) .'</pre>');
drupal_set_message('<pre>'. htmlentities($result->data) .'</pre>');
These should print the request and response. At least you'll know that the quote function is being called... Just remember, drupal_set_message() will display it's output on the *next* page you load; because shipping quotes don't reload the page (since they use AJAX) you'll have to click on a link and go to another page, any other page on your site, to see the messages.

If you do see a request being sent, verify that the content of the XML your site is sending the USPS server is complete, by comparing the content to the test URL. If some info is missing or wrong (say, you haven't set the store address, so the origin ZIP isn't being sent) then you should be able to identify and fix it in the admin settings.

If everything still looks good, you might have a problem with your server setup - is there a proxy? You can test this by executing "curl URL" on your server command line, where URL is the test URL from my previous post.

Stupid questions (that's all I have left...): You did enable the USPS quote method in admin/store/settings/quotes/methods ? And enable quotes for some of the services at admin/store/settings/quotes/methods/usps ? workflow_ng module is installed?

What version did you revert back to?

Keep in mind I have the latest running from Wed 2008-01-02 @ 7:10:39. I just reverted an older uc_usps.module file and it works. Was there any major changes in the new file?

The older file is attached

I dropped the code attached to alien73's post and my flat rate calculation was restored! Unfortunately, the USPS quote still is not working.

Now, there is a problem with the flat rate calculation now. The review order screen is showing the store default flat rate NOT the rate from the product--which in my test case was different. Makes unhappy customers to show different shipping costs between checkout and review order screens.

Ah, that's what's going on. Thanks for isolating the changes.

I made that change because the Workflow-ng configurations were being enabled but the shipping methods weren't. Go to the Shipping quotes methods settings and resubmit that form. It should just be a matter of enabling the ones you want. I had expected that everyone would have done that already, so I didn't think changing the default value would affect anyone.

So you have a 'uc_quote_enabled' row in your variable table, and it includes "usps" in it somewhere?

The database table "variable" has two columns: name and value. Does yours have a row with name = "uc_quote_enabled" and a value that contains "usps"?

Mine is, too. I've resubmitted the forms for all shipping quote methods. I'm still not getting the shipping quote.

Thanks. I did the deactivate/reactivate, revert to defaults in workflow-ng. Problem of shipping calculations is resolved. However, when I click review cart, I get a number of errors preceeding a comment that I didn't select a shipping method.

I was using the version attached by alien73 to an earlier message. When I returned to the 12-31 module file from bazaar, no shipping calculations were performed.

Try deleting your cart then enter a new product then if you get the same error refresh your browser. This worked for me also. Almost a cache thingy

I would bet money it's something to do with workflow_ng

I uploaded workflow_ng 1.6 to my site and found, after resetting the USPS quotes did get reasonable quotes! One problem I am asking for quotes for both parcel post and priority mail. The parcel post quote is always the higher of the two.

Also, once I do select the shipping method and click on the review checkout button, I am presented with a list of 22 error messages all from line 244 of ubercart/uc_store/includes/simplexml.php. This is followed by a message telling me that I didn't select the proper shipping method.

The checkout process works well with the flatrate quote method, except that the review order page always selects the default flat rate shipping even when the product has its own shipping rate.

I'd really, really like to see this fixed and am happy to do some testing with modified code.

The "Edit" form has the setting for enabling or disabling the configuration. It's a confusing interface, because the name of the configuration links to the conditions and actions.