How to provision app web list permissions in a SharePoint Hosted app

Hi

I have a SharePoint Hosted app where I provision a custom list instance to the app web using c#/CSOM.  I am on a local server hosting SharePoint 2013 and Visual studio 2012.  The app works as designed - list provisioned and remote event receivers function.  I am now trying to have the app provision permissions.

I am trying to use the appinstalled event to break inheritence on the list and modify permissions through CSOM.

My first problem is an error - "the remote name could not be resolved: app-guid.appurl" on ClientContext.ExecuteQuery();. 

I am assuming once I access the web object and get the list, I can use list.BreakRoleInheritance(true,false) and then change permissions?  Or, am I on the wrong track completely?

Here is a code segment to illustrate where I am having trouble getting the web object.

using Microsoft.SharePoint.Client;
using Microsoft.SharePoint.Client.EventReceivers;
namespace RemoteEventAppWeb.Services
{
    public class AppEventReceiver : IRemoteEventService
    {
        public SPRemoteEventResult ProcessEvent(SPRemoteEventProperties properties)
        {
            SPRemoteEventResult result = new SPRemoteEventResult();
            if (properties.EventType== SPRemoteEventType.AppInstalled)
            {
                ClientContext clientContext = new ClientContext(properties.AppEventProperties.AppWebFullUrl);
                        if (clientContext != null)
                        {
                            Web web = clientContext.Web;
                            clientContext.Load(web);
                            clientContext.ExecuteQuery();//ERROR!                            
                        }                       
            }
            return result;
        }
        public void ProcessOneWayEvent(SPRemoteEventProperties properties) { }
    }
}
Thanks