Hey. I have used the following validation rules.
Billing_Country_Validation_Rule (1). Validation Formula: NOT(OR(BillingCountry = "US", BillingCountry = "USA", BillingCountry = "United States", ISBLANK(BillingCountry))) ------------------------------------------------------------------------------------------------------

(2).Billing_State_Validation_Rules
OR( LEN(BillingState) <>3, NOT(CONTAINS("AL:AK:AZ:AR:CA:CO:CT:DE:DC:FL:GA:HI:ID:" & "IL:IN:IA:KS:KY:LA:ME:MD:MA:MI:MN:MS:MO:MT:NE:NV:NH:" & "NJ:NM:NY:NC:ND:OH:OK:OR:PA:RI:SC:SD:TN:TX:UT:VT:VA:" & "WA:WV:WI:WY:PR", BillingState)) ) ------------------------------------------------------------------------------------------------------- (3).For_Customer_Channel
ISCHANGED( Name ) && ISPICKVAL(Type, 'Customer - Channel') ------------------------------------------------------------------------------------------------------ (4).For_Customer_Direct
ISCHANGED( Name ) && ISPICKVAL(Type, 'Customer - Direct' ) ----------------------------------------------------------------------------------------------------- (5).Shipping_Country_Validation_Rule
NOT(OR(ShippingCountry = "US", ShippingCountry = "USA", ShippingCountry = "United States", ISBLANK(ShippingCountry))) ---------------------------------------------------------------------------------------------- (6).Shipping_State_Validation_Rule
OR(LEN(ShippingState)<>2, NOT(CONTAINS("AL:AK:AZ:AR:CA:CO:CT:DE:DC:FL:GA:HI:ID:" & "IL:IN:IA:KS:KY:LA:ME:MD:MA:MI:MN:MS:MO:MT:NE:NV:NH:" & "NJ:NM:NY:NC:ND:OH:OK:OR:PA:RI:SC:SD:TN:TX:UT:VT:VA:" & "WA:WV:WI:WY:PR", ShippingState)) )

But I get the following error: Challenge Not yet complete... here's what's wrong:
A validation rule did not prevent a new Account from being saved when Billing Country is blank and Billing State has three characters.

Pls help in fixing it.

I'm unable to check step 2: Automate Accounts because I'm receiving this error: Challenge Not yet complete... here's what's wrong: 
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: ZKCVFIZH