cellulose builder don'r run

[carmen.di...@gmail.com]

Dear all,
I'm trying to run Cellulose builder by the following steps but unsuccessfully:
1) I installed Octave on Centos by yum
2) I downloaded NAMD
3) when I am in dir cellulose_ builder,  I set on the  terminal:
export NAMD="/home/carmendigi/Desktop/NAMD/"


this the error after the command : ./cellulose-builder.sh
 cellulose-builder Copyright (C) 2012-2013 Thiago C. F. Gomes
 This program comes with ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
 FITNESS FOR A PARTICULAR PURPOSE. This is free software, and you are welcome to
 redistribute it under certain conditions; see `license` for details.

 See http://code.google.com/p/cellulose-builder for installation, usage
 instructions and mailing list.

 Please, make sure psfgen is installed and in your PATH.
 See http://www.ks.uiuc.edu/Research/namd/

 That is necessary in order to run this script.
 Make sure the above program(s) are installed and that they are in your PATH.

Can you help me?
Thank you in advance
Carmen