Incremental ingestion not sum up the amount

I am tried to sum the total by using +1 and -1 in my validity but it not working.

Example, i have +1 on 21/3/2020 and got -1 on 15/5/2020 for customer A, it suppose become 0 if i query the total, but this not working. How can I make this happened?

“name”: “validity”,
“type”: “longSum”,
“fieldName”: “validity”

Currently my workaround is re-ingest full table and this will take around 2 hours to complete it as not suitable for production for long term.

Appreciate some advise from expert.