Why is the output value 0?

[Sxbbb]

=Aggr(if([Average] <= [Spec (Upper limit)] and [Average] >= [Spec (Lower limit)],1,0),Id)) 

and This 

=Sum(Aggr(if([Average] <= [Spec (Upper limit)] and [Average] >= [Spec (Lower limit)],1,0),Id))

Same this return is 0. 

Why is the resulting value not sum the value 1 return the loop if ?