Hi, I want to back translate a protein sequence using emboss backtranambig which is a part of nd5 in Aneides flavipunctatus, according to NCBI I must use this Genetic code table but when I use vertebrate mitochondria in the mentioned tool I got in the result some amino acids i.e Y,N, H ...

   >MNYMLIFNSSLMMSIFLLLIPLILNSTNNTSWYMFVKSSIKLSFIVSLLPLMIFLSQGMESTATNLNLFTIYNFNISFSMKIDQYSILFLPVALFVTWAILEFAMWYMSKDLMINQFFKYLLLFLIAMMILVTANNMFQLF

>EMBOSS_001
ATGAAYTAYATGYTNATHTTYAAYWSNWSNYTNATGATGWSNATHTTYYTNYTNYTNATH
CCNYTNATHYTNAAYWSNACNAAYAAYACNWSNTGGTAYATGTTYGTNAARWSNWSNATH
AARYTNWSNTTYATHGTNWSNYTNYTNCCNYTNATGATHTTYYTNWSNCARGGNATGGAR
WSNACNGCNACNAAYYTNAAYYTNTTYACNATHTAYAAYTTYAAYATHWSNTTYWSNATG
AARATHGAYCARTAYWSNATHYTNTTYYTNCCNGTNGCNYTNTTYGTNACNTGGGCNATH
YTNGARTTYGCNATGTGGTAYATGWSNAARGAYYTNATGATHAAYCARTTYTTYAARTAY
YTNYTNYTNTTYYTNATHGCNATGATGATHYTNGTNACNGCNAAYAAYATGTTYCARYTN
TTY

*What is wrong? why the back translation is not well? any suggestion? or another tool to do it ? *