Error in Web Service Java SOAP in GlassFish

I have the following method in a SOAP Web Service running through GlassFish 4.1.1:

@WebService(serviceName = "CalculatorWS")
@Stateless()
public class CalculatorWS {

    @WebMethod(operationName = "add")
    public int add(@WebParam(name = "i") int i, @WebParam(name = "j") int j) {
        return i + j;
    }
}

When you try to run it, the following error is returned to me:

What should I do?