Just my 2 cents Idea :

Did you check your path ?
Did your try your script from different directories ?
You should try it with explicit paths :

#Is package present & available?
@db = `/mybin/more $rxdb`;
[download]

"nothing happens" You didn't get any report by mail ?

Anyway when I don't know what's going on, I usually put print statement everywhere
to display the content of the main variables
(enclosed by visible chars : brace,bang...to see leading/trailing spaces)
to see if they're defined and comply to what I expect...

"Only Bad Coders Code Badly In Perl" (OBC2BIP)