Problem compiling AWS S3 on iOS

Hi,

I'm getting this error when I'm trying to build my iOS project in Xamarin. It was working, then it stopped, I guess I need to roll back something? Or am I missing a package?

Thanks

/Users/me/Projects/MyProject/iOS/MTOUCH: Error MT2002: Failed to resolve "System.Net.IWebProxy Amazon.Runtime.IClientConfig::GetWebProxy()" reference from "AWSSDK.Core, Version=3.3.0.0, Culture=neutral, PublicKeyToken=885c28607f98e604" (MT2002) (MyProject.iOS)