Calculated column: week number of a fiscal year

Question

My fiscal year begins April 01 and ends March 31. How do I create a calculated column in Power BI that will create a fiscal calendar week number?

My calculated column:

WeeKFY = 
VAR WeekStartinFY =
  WEEKNUM ( DATE ( Calendar_Lookup[FYearNumber], 4, 1 ), 2 )
RETURN
IF (
    Calendar_Lookup[Week No] < WeekStartinFY,
    WeekStartinFY +  Calendar_Lookup[Week No]
        + 1,
     Calendar_Lookup[Week No]- WeekStartinFY
        +1
)

The issue is that WeekFY column for 08 January 2017 is gives 17 as a week number instead of 40.

Screenshot of Results