How can I do 'last year to date' calculations for future dates using offsets?

Hi, I want to be able to compare counts of distinct users based on where we were last year vs where we are this year. The dimension field I'm splitting this by is a date they sign up for, so it extends into the future, and we break down the year into seasons.

I can't understand why using OFFSET isn't working here, can anyone help?

Code for the table calc is:

LOOKUP(COUNTD(
    IF [Order Rcvd Timestamp] < DATEADD('year', -1, TODAY())
    THEN [User ID] END
),-1)

Thanks,

Mike.