iOS SOAP null returned problem from unity 4.6.9p4

MyExampleFunc() is works well from unity editor. but returned null from iOS Device.

What should I do? If you help me thank you.

my code>>

 [System.Web.Services.WebServiceBinding(Name="MyExampleSoap", Namespace="http://~~~/")]
     [System.Diagnostics.DebuggerStepThroughAttribute()]
     [System.ComponentModel.DesignerCategoryAttribute("code")]
     public partial class MyExampleClass : System.Web.Services.Protocols.SoapHttpClientProtocol
     {
         public MyExampleClass() {
             this.Url = "http://~~~/~~~/~~~.asmx";
         }
     
 [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://~~~/MyExampleFunc", RequestNamespace="http://~~~/", ResponseNamespace="http:/~~~/", ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped, Use=System.Web.Services.Description.SoapBindingUse.Literal)]
         [return: System.Xml.Serialization.XmlElementAttribute("EventResult")]
         public EventResult MyExampleFunc(int param1, string param2) {
             object[] results = this.Invoke("MyExampleFunc", new object[] {
                         param1,
                         param2});
             return ((EventResult)(results[0])); // results[0] == null
         }
     }

my dll >> System.Data.dll (version 3.0.40818.0)

System.Web.Services.dll (version 3.0.40818.0)

my player settings>>