Problems with USPS and Checkout

I am trying to test the USPS shipping provider but I getting silly errors about my zip code.

Error is as follows:
    
USPS Error returned: Error Desc: Please enter a valid ZIP Code for the sender. USPS Help Context: 1000440.
I have tried to enter both way of zipcode fomat
way 1:  xxxxx    way 2: xxxxx-xxxx
and get the same error

I am using the http://testing.shippingapis.com/ShippingAPITest.dll URL for the USPS Shipping Provider URL

Please help!

After you register your account with USPS, you'll have access to their test servers, which support only "canned" tests, meaning that the test servers will only accept certain request data.

Valid values for testing.
URL: http://testing.shippingapis.com/ShippingAPITest.dll
Zip to = "20008";
Zip from ="10022";
Weight = 2;

thank yo for your fast respond for help
as your instruction, I tried the testing setup as follow

ShippingRateComputationMethod.USPS.DefaultShippedFromZipPostalCode :20022

ShippingRateComputationMethod.USPS.Password: mypassword

ShippingRateComputationMethod.USPS.URL : http://testing.shippingapis.com/ShippingAPITest.dll

ShippingRateComputationMethod.USPS.Username: myusername

in the product variants if the product where the Weight [lb(s)]: I set the Weight [lb(s)]:2

I created a test account with zipcode 20008
I use the test account to check out the product that i set the Weight [lb(s)]: 2
and come up this error:
USPS Error returned: Error Desc: Please enter a valid weight in pounds. USPS Help Context: 1000440.

thank you for your help