[SalesForce] web service callout failed error

I'm having an issue with the Address Verification method available through StrikeIron. I imported the following WSDL and am using the generated wsdl2apex code.

The WSDL I'm using is here: http://wsparam.strikeiron.com/USAddressVerification5?WSDL

I'm calling the VerifyAddressUSA method like this(took out my real credentails):

StrikeIron.USAddressVerificationSoap stub= new StrikeIron.USAddressVerificationSoap();

        StrikeIron.VerifyAddressUSAResponse_element response = new StrikeIron.VerifyAddressUSAResponse_element();

        response=stub.VerifyAddressUSA('','MYEMAIL@MYDOMAIN.COM', 'PASSWORD', '1600 Pennsylvania Avenue', '', ' Washington, DC 20500', '', '', 'PROPER');

The error I'm getting is:

System.CalloutException: Web service callout failed: Unable to parse callout response.    Apex type not found for element http://www.strikeiron.com=AddressLine1

Any ideas on how to solve this? I'm not sure where the problem is.

Thanks!

EDIT(code for VerifyAddressUSA):

public StrikeIron.VerifyAddressUSAResponse_element VerifyAddressUSA(String UnregisteredUserEmail,String UserID,String Password,String AddressLine1,String AddressLine2,String CityStateZIPCode,String Firm,String Urbanization,String Casing) {
        StrikeIron.VerifyAddressUSA_element request_x = new StrikeIron.VerifyAddressUSA_element();
        StrikeIron.VerifyAddressUSAResponse_element response_x;
        request_x.UnregisteredUserEmail = UnregisteredUserEmail;
        request_x.UserID = UserID;
        request_x.Password = Password;
        request_x.AddressLine1 = AddressLine1;
        request_x.AddressLine2 = AddressLine2;
        request_x.CityStateZIPCode = CityStateZIPCode;
        request_x.Firm = Firm;
        request_x.Urbanization = Urbanization;
        request_x.Casing = Casing;
        Map<String, StrikeIron.VerifyAddressUSAResponse_element> response_map_x = new Map<String, StrikeIron.VerifyAddressUSAResponse_element>();
        response_map_x.put('response_x', response_x);
        WebServiceCallout.invoke(
          this,
          request_x,
          response_map_x,
          new String[]{endpoint_x,
          'http://www.strikeiron.com/VerifyAddressUSA',
          'http://www.strikeiron.com',
          'VerifyAddressUSA',
          'http://www.strikeiron.com',
          'VerifyAddressUSAResponse',
          'StrikeIron.VerifyAddressUSAResponse_element'}
        );
        response_x = response_map_x.get('response_x');
        return response_x;
    }

VerifyAddressUSAResonse_element

 public class VerifyAddressUSAResponse_element {
        public StrikeIron.SIWsOutputOfUSAddress VerifyAddressUSAResult;
        public StrikeIron.SISubscriptionInfo SISubscriptionInfo;
        private String[] VerifyAddressUSAResult_type_info = new String[]{'VerifyAddressUSAResult','http://www.strikeiron.com','SIWsOutputOfUSAddress','0','1','false'};
        private String[] SISubscriptionInfo_type_info = new String[]{'SISubscriptionInfo','http://www.strikeiron.com','SISubscriptionInfo','1','1','false'};
        private String[] apex_schema_type_info = new String[]{'http://www.strikeiron.com','true','false'};
        private String[] field_order_type_info = new String[]{'VerifyAddressUSAResult','SISubscriptionInfo'};
    }

VerifyAddressUSA_element

public class VerifyAddressUSA_element {
        public String UnregisteredUserEmail;
        public String UserID;
        public String Password;
        public String AddressLine1;
        public String AddressLine2;
        public String CityStateZIPCode;  
    public String Firm;
    public String Urbanization;
    public String Casing;
    private String[] UnregisteredUserEmail_type_info = new String[]{'UnregisteredUserEmail','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] UserID_type_info = new String[]{'UserID','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] Password_type_info = new String[]{'Password','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] AddressLine1_type_info = new String[]{'AddressLine1','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] AddressLine2_type_info = new String[]{'AddressLine2','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] CityStateZIPCode_type_info = new String[]{'CityStateZIPCode','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] Firm_type_info = new String[]{'Firm','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] Urbanization_type_info = new String[]{'Urbanization','http://www.w3.org/2001/XMLSchema','string','0','1','false'};
    private String[] Casing_type_info = new String[]{'Casing','http://www.strikeiron.com','CasingEnum','0','1','false'};
    private String[] apex_schema_type_info = new String[]{'http://www.strikeiron.com','true','false'};
    private String[] field_order_type_info = new String[]{'UnregisteredUserEmail','UserID','Password','AddressLine1','AddressLine2','CityStateZIPCode','Firm','Urbanization','Casing'};
}