DateAdd does not work across year boundaries

Hi,

I have found that I cannot use a DateAdd to find a date outside of the current year.

Being the 31st Jan 2017 today, if I use (custom column)

DATEADD('Data'[Today].[Date],-3,month) It returns a blank value however

DATEADD('Data'[Today].[Date],-1,day) correctly returns yesterday.

Even DATEADD('Data'[Today].[Date],2,Year) returns a blank value.

Surely we should be able to dateadd across the boundary of the year.

Thanks

Kirsty