Prometheus alert not working properly as like windows task schedular

Hi ,

here is issue related to my metrics showing total quantity . but alert showing partial quantity .
my PromptQL : sum by(bus_no, cause_code) (round(increase(total_calls_disconnected_count_Test[3m])),1.0) > 0

total_calls_disconnected_count_Test metrics : showing 52 count
Mailing alert showing FIRING =36
[1] Resolved mail showing =16

totaly mail quantity shows wrong . anyone can support .

thanks
vilas