SAMEPERIODLASTYEAR expects a contiguous selection when the daye colum is not unique error

[Anonymous]

Hey guys... Is there anyone who can help me solve the error above? I have a table that has a date colum and I don't think any of the rows are empy or are in a different format... Anyone know what the issue could be? 

[lbendlin]

You are supposed to use a calendar table with contiguous dates and full coverage of both the source and the result of any time intelligence calculation.