[Exim] what's wrong with this condition?

What's wrong with:

  condition = "${if \
                        and { \
                                ${if \
                                        or { \
                                                {match {$h_precedence:} {(?i)junk|bulk|list}} \
                                                {eq {$sender_address} {}} \
                                                {match {$h_subject:} {(ADV|Adv|SPAM)}} \
                                        } \
                                        {no}{yes} \
                                } \
                                { yes } \
                        } \
                        {yes}{no} \
                }"

(note that one { yes } is there to make it simpler, I want to put some lookup
there as soon as I find out why this doesn't work)

failed to expand condition "${if and { ${if or { {match {$h_precedence:} {(?i)junk|bulk|list}} {eq {$sender_address} {}} {match {$h_subject
:} {(ADV|Adv|SPAM)}} } {no}{yes} } { yes } } {yes}{no} }" for uservacation router: subcondition in {} expected inside "and{...}" condition

subcondition in {} - everything here is in {} so not helpful message ;)
--
Arkadiusz Miśkiewicz     CS at FoE, Wroclaw University of Technology
arekm.pld-linux.org, 1024/3DB19BBD, JID: arekm.jabber.org, PLD/Linux