The total mode in a pivot table is expression total, you can't set it to sum of rows in expression tab like for a straight table chart.
But you can reproduce a sum-of-rows using advanced aggregation (i.e. the aggr() function). There is a chapter in the HELP that describes this (sum-of-rows in a pivot using advanced aggregation).
Your expression then looks like:
You might also be able to use something like
in your special case where all lines are the same amount.
Hope this helps,