UTR Library Designer Error

Template 5'-UTR Sequence (25NT) : TTTAACTTTAAGAAGGAGATATACC ,     Additional Constraints for designing 5'-UTR sequence (25NT) : TTTAACTTTAAGAAGGAGATNNNNNN ( Length should be 25NT )

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

16s rRNA Sequence : ACCUCCUUA

Desired Expression Range : 500000.00 ~ 999999.00

Number of expression-level intermediates : 16