I am writing following code: import com.paypal.sdk.profiles.APIProfile; import com.paypal.sdk.services.CallerServices; import com.paypal.soap.api.AbstractResponseType; import com.paypal.soap.api.BasicAmountType; import com.paypal.soap.api.CountryCodeType; import com.paypal.soap.api.CreditCardDetailsType; import com.paypal.soap.api.CreditCardTypeType; import com.paypal.soap.api.CurrencyCodeType; import com.paypal.soap.api.DoDirectPaymentRequestDetailsType; import com.paypal.soap.api.DoDirectPaymentRequestType; import com.paypal.soap.api.ErrorType; import com.paypal.soap.api.PayerInfoType; import com.paypal.soap.api.PaymentActionCodeType; import com.paypal.soap.api.PaymentDetailsType; import com.paypal.soap.api.PersonNameType; /** * @author Administrator * */ public class MainClass { /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub try{ DoDirectPaymentRequestType reqType=new DoDirectPaymentRequestType(); DoDirectPaymentRequestDetailsType reqDetails=new DoDirectPaymentRequestDetailsType(); reqDetails.setIPAddress("192.168.20.111"); reqDetails.setPaymentAction(PaymentActionCodeType.Sale); //caller =APICallerFactory.createAPICaller(); CreditCardDetailsType ccdt=new CreditCardDetailsType(); ccdt.setCreditCardNumber("4300754182943440"); ccdt.setExpMonth(2); ccdt.setExpYear(2017); ccdt.setCreditCardType(CreditCardTypeType.Visa); ccdt.setCVV2("000"); PayerInfoType pit=new PayerInfoType(); PersonNameType pnt=new PersonNameType(); pnt.setFirstName("Test"); pnt.setLastName("User"); pit.setPayerName(pnt); pit.setPayerCountry(CountryCodeType.US); ccdt.setCardOwner(pit); reqDetails.setCreditCard(ccdt); PaymentDetailsType pdt=new PaymentDetailsType(); BasicAmountType bat=new BasicAmountType(); bat.set_value("100"); bat.setCurrencyID(CurrencyCodeType.USD); pdt.setOrderTotal(bat); reqDetails.setPaymentDetails(pdt); CallerServices service=new CallerServices(); reqType.setDoDirectPaymentRequestDetails(reqDetails); service.initialize(); APIProfile profile; profile=com.paypal.sdk.profiles.ProfileFactory.createSignatureAPIProfile(); profile.setAPIUsername("amitkh_1186393112_biz_api1.gmail.com"); profile.setAPIPassword("EJ3ESQGMMSP52XTF"); profile.setSignature("ACkj.RIGSOpVjDd8u04rMn1GL518ACrAYHXxBnDHAqzGx7eRByGPxqBm"); //service.initialize(); service.setAPIProfile(profile); AbstractResponseType rt=service.call("doDirectPayment", reqType); ErrorType[] ert=rt.getErrors(); for(ErrorType er:ert){ System.out.println(er.getErrorCode()); System.out.println(er.getShortMessage()); } System.out.println(); } catch(Exception e){ System.out.println(e); } } } I am getting response: - doDirectPayment sent - doDirectPayment Ack : Failure Elapsed Time : 3,828 ms - doDirectPayment Error : This transaction cannot be processed due to an invalid merchant configuration. 10501 Invalid Configuration Please guide where I am wrong