You're assigning an anonymous array, which contains an anonymous hash, to a hash called %paramfields. That's not right. I assume you want something like this:

my @paramfields = ({
        'this'          =>  'thisvalue',
        'that'          =>  'thatvalue',
        'something'     =>  'somevalue'
});

my $result = $server->call($method, @paramfields);
[download]