calculate date is two days ahead.

Hello friends.

I've made a ini file for this site http://bnt1.bnt.bg/bg/programata/bnt1/
For index_showsplit.scrub
i use:
index_variable_element.modify {calculate(format=date,yyyy-MM-dd)|'urldate'}

The date instead of 2018-12-10 is 2018-12-12
Why?
I tried with two different versions of the program on two different computers.
Apparently I'm messing up somewhere. Can somebody help me?
Thanks!