COUNTIFS Issue w/multiple date conditions

I am attempting to: Count all unique text values in the range: B2:B21 that fall between 2 dates specified in the range A2:A21. Using the following:

=COUNTIFS(DATA!B2:B21,"<>"&" ",DATA!A2:A21,">=1/1/2016", DATA!A2:A21,"<=12/31/2016")

I'm able to get the total count, but haven't sucessfully been able to get a unique count to function.

This has got me hung up slightly.

Any help would be largely appreciated.

Thanks in Advance.

J