I drew a small webservice out of my dev  org and consumed it into another ...It doesnt have login method so i also  drew a second enterprise type wsdl  and consumed it also into the other dev org ..So the login problem got sorted as i can see my debug log, but my method gives me null poiter dereferencing error "System.NullPointerException: Attempt to de-reference a null object  "  

My method goes like this and its written in future method ...

enterpriseSoapSforceCom.LoginResult lr= new enterpriseSoapSforceCom.LoginResult();
      enterpriseSoapSforceCom.Soap Esoap= new enterpriseSoapSforceCom.Soap();      
    //  try
     // {       
       lr=Esoap.login(username,password);
       //lr.serverUrl;
       //lr.sessionId;
       system.debug('lr.userId'+lr.userId);
       system.debug('lr.sessionId'+lr.sessionId);       
       system.debug('lr.userId'+lr.userId);
       //MYWebservice34.SessionHeader_element sh = new MYWebservice34.SessionHeader_element();
       //sh.sessionId=lr.sessionId;
      // String authEndPoint = Esoap.Url;
    //  }
     // catch (SoapException e)
     // {
       // Console.WriteLine('An unexpected error has occurred: ' + e.Message + '\n' + e.StackTrace);
     // }
      soapSforceComSchemasClassMywebservi.Account myass= new soapSforceComSchemasClassMywebservi.Account();
      Account a=[Select BillingCity,Name,BillingCountry,BillingPostalCode,BillingStreet,Phone,Site from Account where id=:aa Limit 1];
      //soapSforceComSchemasClassMywebservi.BillingCity=a.BillingCity;
      myass.Name=a.Name;    
      //myass.BillingCountry=a.BillingCountry;
      //myass.BillingPostalCode=a.BillingPostalCode;
      //myass.BillingStreet=a.BillingStreet;
      //myass.Phone=a.Phone;
      //myass.Site=a.Site;
      soapSforceComSchemasClassMywebservi.MyWebService  Serv=new soapSforceComSchemasClassMywebservi.MyWebService ();
      Serv.SessionHeader.sessionId=lr.sessionId;
      Serv.makeContact('Rick',myass);  //error occurs here ....

 Help needed ....

What could be possible reason .....

Code of my webservice is this ....

global class MyWebService 
{
    webService static Id makeContact(String lastName, Account a) 
    
    {
        Contact c = new Contact(lastName = 'Weissman',firstname = a.Name);
        insert c;
        return c.id;
    }
    
}

It simply receives a string and an account which i am sending  from the other org as given above ..

Thanks