UTR Library Designer Error

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

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

16s rRNA Sequence : ACCTCCTTT

Desired Expression Range : 1002.55 ~ 2816266.40 ( Desired max expression should be smaller than 1000000 )

Number of expression-level intermediates : 64