Aside from the syntax error at %hash{"my_function"} that should work: 
#!perl -w
use strict;

sub my_func {
    print @_;
}

my %hash = (
"my_function" => \&my_func
);

my $func_ref = $hash{"my_function"};

&$func_ref("bla");

[download]
but I prefer to do $func_ref->("bla")

Had you posted a working code snipped, chances are you'd have found out for yourself ;-)

"What should it profit a man, if he should win a flame war, yet lose his cool?"

In reply to Re: Calling a function reference with arguments by Joost
in thread Calling a function reference with arguments by Zubinix

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