iOS 64bit build with WebRequest.Create()

I amd testing iOS 64build on Unity 4.6.2. When I run my app on device and call the image's method, I got the Xcode error.

I think It's the stripping problem. So I made Assets/link.xml.

 <assembly fullname="System">
     <type fullname="System" preserve="all"/>
     <type fullname="System.Net" preserve="all"/>
     <type fullname="System.Net.Cache" preserve="all"/>
     <type fullname="System.Net.Configuration" preserve="all"/>
     <type fullname="System.Net.Mail" preserve="all"/>
     <type fullname="System.Net.Mime" preserve="all"/>
     <type fullname="System.Net.NetworkInformation" preserve="all"/>
     <type fullname="System.Net.NetworkInformation.MacOsStructs" preserve="all"/>
     <type fullname="System.Net.Security" preserve="all"/>
     <type fullname="System.Net.Sockets" preserve="all"/>
     <type fullname="System.Web" preserve="all"/>
     
     
 </assembly>
 <assembly fullname="System.Configuration">
     <type fullname="System" preserve="all"/>
     <type fullname="System.Configuration" preserve="all"/>
     <type fullname="System.Configuration.Internal" preserve="all"/>
     <type fullname="System.Configuration.Provider" preserve="all"/>
 </assembly>

It is my link.xml. Do I need add more? Or It's Unity's bug? Please, let me know.