FEDEX Shipping Extension Issue

Sorry, it seems that there are no available shipping methods for your location (United States). If you require assistance or wish to make alternate arrangements please contact us.

Hi Guys. Any help for this error..??
I am trying it for around 3 days.. but no luck…
what i have done till now is:

Set Countries: United States(However tried implementing All Countries too)
My base Country is : US
Currency: Dollars(US)

Please help.. All is completed except this…