[exim] Rewrite confision

I'm missing something here and I don't understand why this isn't
working. This part in a rewrite rule works:

*@plf.net ${lookup{$1}dbm{/etc/exim/control/run/test2.db}{$value}fail} Ttcb

test2.db contains:

code3: marc@???
code2: support@???

But this doesn't work:

*@plf.net
${lookup{$sender_address}dbm{/etc/exim/control/run/test1.db}{$value}fail}@???
Ff

test1.db contains

marc@???: code3
support@???: code2

What am I missing? Thanks in advance.