Hard to tell without seeing the dimensions/structure of the source module as well as the dimensions of the module you've shared. Can you post blueprints of both?
Also, something to note about the TIMESUM function arguments, though I'm not sure if it's relevant here:
If you use a date value for either theStart periodorEnd periodargument, their positions are swapped. This means that theEnd periodargument should be a date in the period when aggregation begins andStart periodshould a the date in the period when aggregation ends.