Calender date not correct

i’m using framework 7 Calendar / Datepicker for my application.
i use calendarType: “jalali” .
the problem is that the whole calender is one year behind.
for example 1398/01/01 is in fact Saturday but in this calender 1398/01/01 is Friday but 1397/01/01 in this calender is Saturday and is the right one.
how can i shift the whole year one year back?