Converting between the Gregorian and Julian calendars, I sometimes get results which don't seem to make sense.

I have seen the instructions for CalendarConvert and tried to follow the instructions. I used 1584, 1, 8, which should be January 8, 1584. CalendarConvert[DateObject[{1584, 1, 8}], "Julian"

The result was, Wolfram|Alpha doesn't understand your query.

I've tried the more conventional format and it sometimes worked. This did seem to work: convert julian date January 2, 1584 to the Gregorian calendar Julian calendar | Thursday, January 12, 1584 (Gregorian calendar)

Then I tried 2 January, 11584 and got Tuesday, March 27, 11584

It works for the years 1000, 900, 800...100, but when I try Jan. 2, 99 AD it doesn't understand my query. When I try Jan. 2, 98, it gives me the conversion for 1998. When I try Jan. 2, 15, it gives me the conversion for 2015. And when I try Jan. 2, -115, it has this:

convert convert Saturday, January 2, 115 BC (extrapolated Gregorian calendar) to Julian calendar to Gregorian calendar 5 January, 115 BC (Julian calendar) Saturday, January 2, 115 BC (extrapolated Gregorian calendar)

So it's switching the calendars around.

Is there something I should do differently? Thanks.