I have created an application for Windows Phone 7, it is working well in the devices. Now I planned to Port/Upgrade it to the new Windows Phone 8.

I followed the process mentioned in the following link
http://msdn.microsoft.com/en-US/library/windowsphone/develop/jj207030%28v=vs.105%29.aspx#BKMK_knownissues

Though I followed the process, I am having only one Warning
This is the Warning:
The predefined type 'System.Tuple' is defined in multiple assemblies in the global alias; using definition from 'c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\WindowsPhone\v8.0\mscorlib.dll'

These are the namespace i am using.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using Microsoft.SilverlightMediaFramework.Core.Media;
using Microsoft.Phone.Net.NetworkInformation;
using Microsoft.SilverlightMediaFramework.Core;



I have searched System.Tuple in Object Browser, and I am able to see that all the items are listed twice like Tuple<T1,T2> , Tuple <T1,T2>

I found that Microsoft.SilverlightMediaFramework.Compatibility.Phone and mscorlib.dll contains System.Tuple.

Can anyone help me how to solve this warning?