Missing partial modifier on declaration of type - BizTalk

 Today i came to a problem when consuming webservices. added a web reference instead of service reference got the following error when building the project

Error    1    Missing partial modifier on declaration of type 'project1.WebReference.Service1'; another partial declaration of this type exists    C:\solution\project1\Web References\WebReference\Service1.xsd.cs    8    25    project1

the problem was that there was two service1 datasets when web reference was added. changed the namespace of the other one and compiled . problem solved