[Exim] unseen causes "Unroutable address"

Hello,

I want to run two routers with the following definitions:

all_addresses:
driver = redirect
allow_fail
allow_defer
data =
${lookup{$local_part@$domain}lsearch*@{/vrmd/exim-4.32/allAddresses}}
directory_transport = address_directory
unseen

autoreply_addresses:
driver = accept
condition = ${if
!eq{${lookup{$local_part@$domain}lsearch*@{/vrmd/exim-4.32/autoresponder}}}{}{yes}{no}}
transport = address_autoreply
unseen

My idea is, that both of them work independently. all_addresses results
in storing emails locally or forwards, whatever is received from the
lookup. Since the second router needs to be called, too, I added
"unseen". The autoreply_addresses shall lookup if a autoresponder is
defined for a certain address. If nothing is defined, the router shall
be skipped. Now here's my problem: If an address is defined in
all_addresses, but not in autoreply_addresses, then the second router
isn't just skipped, it causes an "Unroutable address" instead. So the
same message is delivered correct through the first router and then
returns a bounce mail through the second router, although it is
delivered. How can I avoid this?

Regards
Marten