P&L Reports don't add up

Why is it that the net realised profit of 4 months collectively is different then what should be the sum of all 4 month profits?

For ex:- if i see my net realised profits after deducting the changes from 1-jan-2017 to 31-jan-2017 it’s 10 rupees
From 1-feb-2017 to 28-feb-2017 = 10 rupees
from 1-mar-2017 to 31-mar-2017= 10 rupees
from 1-apr-2017 to 30-apr-2017= 10 rupees

This should total to 40 rupees. but when i see the Absolute net realised profit for all 4 of these months collectively
i.e From 1-jan-2017 to 30-apr-2017. instead of showing 40 rupees, it shows 25.