Currently, “Tax & Shipping options” field can have following values:
Shipping methods, which you have set using “Carrier-calculated methods” and “User-defined method” will cost 0.00 for this product
Shipping cost for this product will be taken from “Fixed rate” field.
3. Use Global settings
. Shipping cost will be calculated according to the settings of “Carrier-calculated methods” and “User-defined method”.
4. Global Fixed
. Shipping cost will be calculated as a summary of carrier-calculated or user-defined methods rate and fixed value from “Fixed rate” field.
Thus, if you are going to use USPS method only, you should set “Use global settings” in “Tax & Shipping options” field. In this case shipping cost will be calculated depending on product weight and delivery address.
The reason why shipping methods are not applied for your order now - is incorrect USPS methods setup. If you will go to Ecwid control panel → Shipping → Carrier-calculated methods → USPS, click “Account details” and click “Test” button, you will see “Authorization failure. You are not authorized to connect to this server.” message. Most likely your USPS account is in test mode. Please, refer to this article for details: http://kb.ecwid.com/w/page/15853320/...
Once you will setup USPS method correctly, shipping cost will be calculated as expected.