Hi @Binaya_Chalise
welcome to the forum! Please introduce yourself here!
all those non-Gregorian calendars like Bikram Sambat/Ethiopian/Coptic etc are just appearances. that means dates are displayed in that particular formats but under the hood when you save your form in xml file we use Gregorian dates for all. Because of that creating constraints you need to set Gregorian dates in all the cases no matter what appearance you use.
So your constraint should be like:
.>= date('2013-02-12') and .<= date('2018-01-14')
BikramSambat-export.xlsx (8.1 KB)