perl in procmail

What can possible be wrong with this procmail snippet? The perl 
script works fine from the shell, but from the .procmailrc nothing is
executed. Also how can a variable like WHOFROM be parsed to the perl
program?

WHOFROM=`formail -XFrom: | formail -rtz -xTo:`

:0 hc     
* ^From(_dot_)*someone(_at_)domain(_dot_)com              
| /usr/home/jj/test.pl

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Tomas Karlsson