Make sure to correctly check for null for the time point

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/TrackedRace.java

@@ -107,6 +107,9 @@ public interface TrackedRace extends Serializable {
      * {@link TimingConstants#IS_LIVE_GRACE_PERIOD_IN_MILLIS} is added to that to mark the end of the "live" interval.
      * <p>
      * 
+     * @param at
+     *            the time point at which to determine whether the race for <code>fleet</code>
+     *            is/was live. A <code>null</code> value will use the start time of the race.
      * @return
      */
     boolean isLive(TimePoint at);

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java

@@ -657,7 +657,7 @@ public abstract class TrackedRaceImpl implements TrackedRace, CourseListener {
         }
     
         // if an empty timepoint is given then take the start of the race
-        if (at.asMillis() == 0) {
+        if (at == null) {
             at = new MillisecondsTimePoint(startOfLivePeriod.getTime()+1);
         }