Ubuntu Servers :: Cat Command Gives Error Permission Denied

I am using Ubuntu server edition 10.04.1 running in Vmware server 2.02.I am connect via Putty so I can use copy and paste.My first goal is configuring a ftp server using PureFtpd using this guide.In section 10 I need to write this command

cat /dev/null > /etc/pure-ftpd/db/mysql.conf

I am getting this error

almog@Testing:~$ sudo cat /dev/null > /etc/pure-ftpd/db/mysql.conf
-bash: /etc/pure-ftpd/db/mysql.conf: Permission denied

I tried with and without "sudo" and I am getting the same error.