ideal principal in relative extension

[zekhnini <zekha2@gmail.com>]

Dear users,
 I want to know if the thow ideals M and N are principal in the relative     
extension K=k(sqrt(2+8*i)) of the field k=Q(sqrt(2*17*5),i ). what can I do?

 
  T=polcompositum(y^2+1,y^2-2*17*5)[1];
  k=nfinit(T);
  P=x^2-Mod(y^4-4*y^2+4*17,k.pol);

  K=rnfinit(k,P);
  Keqn=rnfequation(k,P,1)[1];
  Kabs=nfinit(Keqn);          
  
  H1=idealprimedec(k,17)[1];
  H2=idealprimedec(k,17)[2];
  
  M=rnfidealup(K,H1);
  N=rnfidealup(K,H2);


  MK= mathnf( Mat( nfalgtobasis(Kabs, M) ) );
  NK= mathnf( Mat( nfalgtobasis(Kabs, N) ) );

 It responds  nfalgtobasis: incorrect type in algtobasis.
 
Thanks for help.
zekhnini