Data conversion from weekly to daily (Date mismatch)

Hi. I am using Stata 13 and have a question about the “collapse” command and Stata date formatting.
I have a daily time series from January 1971 up to nowadays. Data is from Monday to Friday (weekends omitted). I am trying to convert my daily time series into weekly ones with the object for Stata selecting the last day of the week (which is Friday in my case).

So I used:
gen dw=wofd(date)
collapse (first) var1, by (dw)
format %twMon_DD,_CCYY dw

I discovered that the calendar days are not matching up. Stata has converted dates correctly until December 1971. In that month, it should have picked the 3^rd, 10^th, 17^th, 24^th, and 31^st dates. But for some reason Stata ignored the 31^st (which was Friday and I have data for that day), created the new date January 1^st 1972 and assigned the value from December 31 to January 1st.
From that point downward everything got mismatched i.e. Stata assigned the wrong values to wrong days of the week.

I also tried to use “last” option for “collapse” command with the same result.
Has somebody else been encountered with such a problem? I would appreciate any suggestion how to resolve this issue.

Thank you in advance

P.S. I have attached my data file