[plt-scheme] trouble installing plt v370 on ubuntu

I have downloaded the plt-370-bin-i386-linux-ubuntu-feisty.sh and run
it in the terminal where i meet the prompts below:



Do you want a Unix-style distribution?
  In this distribution mode files go into different directories
according
  to Unix conventions.  A "plt-uninstall" script will be generated to
  make it possible to remove the installation.  If say 'no', the whole
  PLT directory is kept as a single (movable and erasbale) unit,
possibly
  with external links into it.
Enter yes/no (default: no) > no

Where do you want to install the "plt" directory tree?
  1 - /usr/plt [default]
  2 - /usr/local/plt
  3 - $HOME/plt (/home/day/plt)
  4 - ./plt (here)
  Or enter a different "plt" directory to install in.



however, after i install it under /usr/plt and run drschme in usr/plt/
bin, it told me that "can not find mred" but mred is in /usr/plt/bin,
it is there. What's the problem. And when i double click mred, nothing
happened. What's wrong?

Ok, i retried to install it this time i answered yes in the prompt.



Do you want a Unix-style distribution?
  In this distribution mode files go into different directories
according
  to Unix conventions.  A "plt-uninstall" script will be generated to
  make it possible to remove the installation.  If say 'no', the whole
  PLT directory is kept as a single (movable and erasbale) unit,
possibly
  with external links into it.
Enter yes/no (default: no) > yes

Where do you want to base your installation of PLT Scheme v370?
  (Use an existing directory.  If you've done such an installation in
   the past, either use the same place, or manually run
   'plt-uninstaller' now.)
  1 - /usr/... [default]
  2 - /usr/local/...
  3 - $HOME/... (/home/day/...)
  4 - ./... (here)
  Or enter a different directory prefix to install in.
> 1

Target Directories:
  [e] Executables   /usr/bin (exists)
  [s] Scheme Code   /usr/lib/plt/collects (will be created)
  [d] Core Docs     /usr/share/plt/doc (will be created)
  [l] C Libraries   /usr/lib (exists)
  [h] C headers     /usr/include/plt (will be created)
  [o] Extra C Objs  /usr/lib/plt (will be created)
  [m] Man Pages     /usr/man (will be created)
Enter a new prefix, a letter to change an entry, enter to continue
>

Checking the integrity of the binary archive... ok.
Unpacking into "/usr/plt-tmp-install"... done.
plt-370-bin-i386-linux-ubuntu-feisty.sh: 488: plt-tmp-install/bin/
mzscheme: not found
Error: installation failed
  (Removing installation files in /usr/plt-tmp-install)



However, an error comes out which asked me to remove installation
files in /usr/plt-tmp-install. But I can't find the file it talks
about. No such file exists. Any idea.

There do exists a drscheme package probided by the Ubuntu community,
but it is v352, out of date. I want to install v370. Can any one help
me?