[galaxy-user] symbolic link to bowtie

Hi, I am running Galaxy locally (Ubuntu 11.04) and I am getting this error message when I try to use mapping with bowtie:

Error indexing reference sequence /bin/sh: bowtie-build: not found

Then I downloaded bowtie and tried to create a symbolic link using at /bin: ln -s /home/koala2/bowtie bowtie

Then I get this error message: ln: creating symbolic link `bowtie': Permission denied

I know that is more a linux issue than Galaxy, but does anyone have any suggestion? I changed the permission of bowtie folder and file but keep getting same error. I am logged as administrator too.

Thank you.

Luciano