Java.Interop.IJavaPeerable error

Hi all;
Any idea how to get rid of this error , I get this when I run my PCL project in iPAD air 2 ?

Severity Code Description Project File Line Suppression State Tool
Error Failed to resolve "Java.Interop.IJavaPeerable" reference from "Java.Interop, Version=0.1.0.0, Culture=neutral, PublicKeyToken=84e04ff9cfb79065" App1.iOS C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\MSBuild\Xamarin\iOS\Xamarin.iOS.Common.targets 777