array flatten error

[dealharris]

This works:

datam:=//statistics/jobs/months
datam1:=datam.Results where datam.JobGroup="Database Administrator"
finalmonth:=flatten(datam1.avgsalbyitskill) with {date:datam.QueryDate}
finalmonth

This doesn’t and its essentially the same data, just in a different collection:

data:=//statistics/jobs/jobgroups
data1:=data.Results where data.JobGroup="Database Administrator" & data.QueryDate="9/31/2013"
finalday:=flatten(data1.avgsalbyitskill) with {date:data.QueryDate}
finalday

This is the error I am getting:

2013-11-01 12:46:51,582 [atcher-148] E c.p.s.s.SyncQueryServiceHandler {} - Error executing shard query:
java.lang.UnsupportedOperationException: empty.max
at scala.collection.TraversableOnce$class.max(TraversableOnce.scala:201)
at scala.collection.immutable.Set$EmptySet$.max(Set.scala:52)
at com.precog.daze.ArrayLibModule$ArrayLib$Flatten$$anonfun$apply$1$$anonfun$2.apply(ArrayLib.scala:33)
at com.precog.daze.ArrayLibModule$ArrayLib$Flatten$$anonfun$apply$1$$anonfun$2.apply(ArrayLib.scala:27)
at scalaz.StreamT$$anonfun$map$1$$anonfun$apply$58.apply(StreamT.scala:82)
at scalaz.StreamT$$anonfun$map$1$$anonfun$apply$58.apply(StreamT.scala:82)
at scalaz.StreamT$Yield$$anon$7.apply(StreamT.scala:215)
at scalaz.StreamT$$anonfun$map$1.apply(StreamT.scala:82)
at scalaz.StreamT$$anonfun$map$1.apply(StreamT.scala:82)
at scalaz.Monad$$anonfun$map$1$$anonfun$apply$1.apply(Monad.scala:14)
at akka.dispatch.Future$$anon$3.liftedTree1$1(Future.scala:195)
at akka.dispatch.Future$$anon$3.run(Future.scala:194)
at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:94)
at akka.jsr166y.ForkJoinTask$AdaptedRunnableAction.exec(ForkJoinTask.java:1381)
at akka.jsr166y.ForkJoinTask.doExec(ForkJoinTask.java:259)
at akka.jsr166y.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:975)
at akka.jsr166y.ForkJoinPool.runWorker(ForkJoinPool.java:1479)
at akka.jsr166y.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:104)