Assistance with the statistics functions

[sts098]

I have a simple chart to display acid dosed to my swimming pool I graphed this sensor which had some null values. I used fill_raw: zero to correct this. I then added a second entity, the same senor. Attempting to sum the values dispensed each day. However, the value displayed is zero. below is the code I used:

`type: custom:apexcharts-card
graph_span: 3d
span:
end: day
header:
show: true
title: ApexCharts-Card
show_states: true
colorize_states: true
now:
show: true
series:

• entity: sensor.pool_controller_chem_acid_dose
  extend_to: now
  fill_raw: zero
  type: column
• entity: sensor.pool_controller_chem_acid_dose
  extend_to: now
  fill_raw: zero
  type: line
  statistics:
  type: sum
  period: day
  align: end
  group_by:
  func: last
  start_with_last: true
  duration: 1d
  fill: zero`

Below is the image:

Any Idea where I am going wrong?