Aggregates not working

[Arizno]

I have an Action that “adds an new row to another table using data from this row”.

I am trying to tally data from a Timesheet table using the below expression, but it is not aggregating the data because it just displays “0”.
SUM(
SELECT(Timesheet[Total Hours], ([_THISROW].[WorkorderID] = [WorkorderID])
))

Any suggestions on how to get this data to do the proper math?