Alarm Manager

I am trying to implement a notification to fire at a fixed point in the future, but I am having difficulties getting it working right. It fires immediately rather than at the specified time in the future. Below is my receiver class. I am calling SetAlarm from another class and passing a time interval, which is alertTime. Any thoughts? Thanks!!!

using System.Linq; using System.Text; using Android.App; using Android.Content; using Android.OS; using Android.Runtime; using Android.Views; using Android.Widget; using Android.Util;

namespace Test_Android { [BroadcastReceiver] class NotificationAlertReceiver : BroadcastReceiver {

    public NotificationAlertReceiver()
    {

    }

    public override void OnReceive(Context context, Intent intent)
    {
        PowerManager pm = (PowerManager)context.GetSystemService(Context.PowerService);
        PowerManager.WakeLock w1 = pm.NewWakeLock (WakeLockFlags.Partial, "NotificationReceiver");
        w1.Acquire ();
        var nMgr = (NotificationManager)context.GetSystemService (Context.NotificationService);
        var notification = new Notification (Resource.Drawable.loadIcon, "Arrival");
        var pendingIntent = PendingIntent.GetActivity (context, 0, new Intent (context, typeof(MainActivity)), 0);
        notification.SetLatestEventInfo (context, "Arrival", "Arrival", pendingIntent);
        nMgr.Notify (0, notification);
        w1.Release ();
    }

    public void CancelAlarm(Context context){ 
        Intent intent = new Intent(context, this.Class);
        PendingIntent sender = PendingIntent.GetBroadcast (context, 0, intent, 0);
        AlarmManager alarmManager = (AlarmManager) context.GetSystemService (Context.AlarmService);
        alarmManager.Cancel (sender);
    }

    public void SetAlarm(Context context, int alertTime){
        long now = SystemClock.CurrentThreadTimeMillis();
        AlarmManager am = (AlarmManager) context.GetSystemService (Context.AlarmService);
        Intent intent = new Intent(context, this.Class);
        PendingIntent pi = PendingIntent.GetBroadcast (context, 0, intent, 0);
        am.Set (AlarmType.RtcWakeup, now + ((long)(alertTime*10000)), pi);
    }
}

}