mail script doesn't run
 

is there any reason why this script will not run. it runs on one of my servers, but not on the others. this is very confusing. here is the scirpt:

//*************************

#!/bin/sh

/bin/mail -s hi.works.report me@yahoo.com << "From: fil
e_compare
To: me@bob.com
Subject: Files are Equal
backup.$HOSTNAME.$DATE.tar at size $SIZE\n"

//*************************

any help would be appreciated. and yes i did check /bin/mail and it looks the same on both servers but only seems to be working on one.