UTR Library Designer Error

Template 5'-UTR Sequence (25NT) : GATCCGAATTCAAGGAGNNNNNNNN ,     Additional Constraints for designing 5'-UTR sequence (25NT) : NNNNNNNNNNNNNNNNNNNNNNNNN

Protein Coding Sequence (at least N-term 35NT) : ATGAACCGTGCGGTACGCCATACTGGCCTTATGCG

16s rRNA Sequence : ACCUCCUUA

Desired Expression Range : 40000.00 ~ 40000.00 ( Desired max expression should be larger than that of min )

Number of expression-level intermediates : 16