Need help displaying two different counts on the same chart

I want to display sales and refunds counts for the same day on the same chart like it is shown on the first picture. The corresponding date fields for sales and refunds are detail_trans_date and detail_refund_date.
I have added new column for refunds but I want it to be counted by detail_refund_date.

I tried to add the following script to the JSON Input:

  "exists": {
    "field": "detail_refund_date"

but nothing has changed.
Any advice on how I can achieve this is appreciated, thanks!

Kibana version is: 5.5.2

Try this: Click on "Add a filter ", then on Field select detail_refund_date and the Operator would be exists.

Hello, thanks for your reply. I tried that but the result is not much different, it just filters out any entries that don't have refunds. See the result in the attached image:

I fixed it by adding two filters
See the attached image