i get the error sh: /opt/zimbra/zdesktop/linux/prism/zdclient: not found

# lsb_release
Description: Ubuntu 11.04
Release: 11.04
Codename: natty

# cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 xubu

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters


Press "Enter" to launch Zimbra Desktop; Press "Ctrl-c" to exit:
sh: /opt/zimbra/zdesktop/linux/prism/zdclient: not found

$ ls /opt/zimbra/zdesktop/linux/prism
application.ini components extensions modules zdclient
chrome defaults fix-linux-stack.pl xulrunner