[exim] Trouble with a match condition

Hi all

I am having a spot of bother getting a match condition to work in an exim
router
here is the router in it's entirity including the match condition.
The condition is always failing and the message is passed to the next router
that directs mail to the ham transport

any assistance much appreciated on this as I am completely stumped

#####################################################
### router/950_exim4-config_virtual_user_spam
#####################################################
# This router matches the virtual users' spam mailboxes

virtual_user_spam:
driver = accept
domains = +local_domains
local_parts = lsearch:/etc/exim4/virtual2/virtual_users_$domain
transport = virtual_localuserspam

condition = ${if match {$h_X-Spam-Status:}{\N/Yes/\N} {yes} fail }

###################################################################
## end router/950_exim-config_virtual_user_spam
###################################################################


Kind Regards
Hill Ruyter