File 'Windows.props' not find

I Created a Empty Xamarin.Forms Portable .This error occurred at compile time. File 'Windows.props' not find。 For more information, see http://go.microsoft.com/fwlink/?prd=12395&pver=1.0&plcid=0x409&ar=MSDN&sar=PlatformMultiTargeting&o1=C:\Program Files (x86)\Microsoft SDKs\Portable\v12.0&o2=Portable。
does anybody know how I can solve this problem