mail queue problem

I recently installed the mail queue package. the install was successful and the package tested fine when running it in my web browser. i used the test files (add_example.php and send_example.php) included in the package. however i wanted to introduce the cron feature so that emails would be sent automatically so i knew that for this feature to work i would have to call the send_example script from the command line. I tried this and i got the following error: "call to undefined method DB_Error::quote() in C:\wamp\php\PEAR\Mail\Quote\Container\db.php". i also tried running the add_example script in the command line just to see what would happen and it produced the same error, not recognising any methods belonging to DB_Error. Im really confused because both these scripts ran fine when i ran them in internet explorer.(i usually save all of my files in a www folder and then call them using the address "http://localhost/the_name_of_the_script.php") anyone know why these scripts might be failing on the command line? any help would be much appreciated! thanks