Why aren't my shipping methods working in my site?

If you are experiencing issues with your shipping methods not working in your site, here are some common causes:

1. No Ship From Location. Make sure you have a Location set up for your facility in Preferences >
2. No weight in your pricing engine.
3. Courier Info Incomplete/Incorrect. If the Shipping Method is using an integrated Carrier
(UPS/FedEx/USPS), in Preferences > Settings > Shipping > Carrier Accounts, make sure the Carrier's
account info is complete and accurate.
4. Shipping Method Min/Max Weights Incorrect. In Preferences > Settings > Shipping > Shipping Methods,
check the Maximum Weight setting for the Shipping Method. Make sure the Maximum Weight is not set
to zero. Make sure the Maximum Weight supports the weight the storefront's calculator is creating based
on the item and quantity selected.
5. Shipping Method "Packaging" is incorrectly set to "Box" for UPS Ground.
6. The Cart May be Too Heavy. The number of items in the cart may exceed the maximum weight for the
available shipping method(s).
7. Shipping Method is not On. Make sure the desired Shipping Method is turned on for the Site. Sites >
Settings > Shipping. The box must be checked for the desired Shipping Method to be available in the
Storefront. At least one Shipping Method needs to be checked. Also check if the shipping method is enabled for appropriate site groups. 
8. Digitally Deliver Edoc File. The product is using an eDocBuilder template and the "Digitally Deliver Edoc
File" option has been check marked.  Either uncheck the "Digitally Deliver Edoc File" option, or
add a new shipping method (non-integrated, 0 min weight, 0 max weight) for items that are being
digitally delivered instead of printed and shipped.
One method you can use to help you determine which of the options noted above would be most helpful towards resolving the issue would be to test the shipping methods that are available on the site.  Gather the details of the items that are in the customer's cart such as the shipping address and the total weight of the items that are included.
Once you have that information, go to SiteName > Settings > Shipping tab and at the bottom of this page you will see a section called "Test Shipping Options".  Add the details from your customer's cart into the fields and click "Test Now".  On the right, the available shipping methods will be displayed and if there are any errors with the shipping methods - these will display in red as well as provide a brief description as to why this shipping method is not available.  This message will usually correspond with one of the items noted above so that the appropriate changes can be made.