Having played around with DAX time intelligence functions, I've got the ‘Function XXXX only works with contiguous date selections’ error a few times. After some email correspondence with Marius Dumitru I understand the reason why this error is occurring, but in at least one case I've found a query where I get the error and I think I should be getting results.
Consider a previous period growth calculation. If you put dates on rows and measures on columns, then for each date you would expect to see the previous period growth calculation return results and you do. Then imagine you want to see growth for all dates in January 2002 and January 2003, so you can compare the growth values - you add year to slice and choose 2002 and 2003, then add month and choose January, and you get the error. However in this case the slicers are only being used to control which dates are being displayed on rows, and it still makes sense to see the result of the calculation for an individual date.