Calculate past 5 week Average

I was trying to generate a 5-week average volume. Does anyone know why the first formula work but not the second one? 

Vol Avg5WK = calculate(Divide(SUM('2014Data'[#Shipments]),5),FILTER(all('2014Data'),'2014Data'[WeekNum]>=MAX('2014Data'[WeekNum])-5 && '2014Data'[WeekNum]<=MAX('2014Data'[WeekNum])-1))

Vol Avg5WK = calculate(Divide(SUM('2014Data'[#Shipments]),5),FILTER('2014Data','2014Data'[WeekNum]>=MAX('2014Data'[WeekNum])-5 && '2014Data'[WeekNum]<=MAX('2014Data'[WeekNum])-1))

The difference is I removed All() from Filter function.

Many thanks!