I posted this in the admin setup forum about a month ago, but did not get a response, so I'm trying here...
UPS methods are showing up fine, but I can't get USPS to show up. I have entered my existing USPS id and password that's working for live rate lookup on my old classic asp site; and when that didn't work, I created a new USPS id and password. I just get the error "This shipping method is currently unavailable ..." I've seen a few other people with this question, but no response from anyone.
I did find something online that indicated that we needed to have PHP Soap extension enabled, and I confirmed that that is enabled on my server. But still no luck.
It's not SOAP, thats not used. You need to switch on the logging and see what the USPS request/response is.
Under USPS switch on the switch "Debug". Then switch on general logging via the admin ( there are plenty of posts on how to do this) and look at the log in /var/log/system.log. The USPS response will give you more info as to whats up.