example code for dodirectpayment api for sandbox account
                            
                         
                        
                     
                 
                
                    
Hello Every one can any one sand me example code for dodirect payment api for sand box.
i make code but always ACK Parameter returns me failure.
 does any settings are required for paypal merchant account to use api.
i have copy the api usernm ,pswd and signature
i make many try and search google but i dont get correct answer 
so plz answer  me its  urgent 
Thnks