Calculating time as a percentage per dimension

[johnnyjohn]

Hi, I've spent a couple of days on this problem now, and can't find a solution.

So I have two tables.

My parent order table:

and my child order table

Basically, what I am trying to do here is calculate the child time as a percent, aggregated by Parent ID. To do this, I calculate the lifetime of the order in seconds (Max ChildTime - Min ChildTime) for each Parent ID, then calculate the time into the life of the order of the child in seconds (ChildTime - MinTime) for each Parent ID, then divide the time of the child by the life time of the order, that gives me the figure I want (mathematically at least).

In QlikSense I have the below: 

Child Time in Second = Num(ChildTime) *24*60*60

First Fill in Second = Num(Aggr(Min(ChildTime),[Ord ID])) *24*60*60

Last Fill in Second = Num(Aggr(Max(ChildTime),[Ord ID])) *24*60*60

But for SOME REASON, when  I try to find my Child Time - First Fill  with this, only a single value shows for the dimension, as shown on the table above

=(Num(ChildTime) *24*60*60) - (Num(Aggr(Min(ChildTime),[Ord ID])) *24*60*60)

Does anyone have any idea why this is happening? Or how I can achieve what I described.

Thanks!!!