SA run cond question

Hello All,
    I'm having some trouble getting sa-exim to quit scanning mail from a 
trusted network.   I have tried toying with both the spamassassin 
trusted_networks parameter in the local.cf and changing the sa-exim run 
condition.  Neither parameter seems to make any difference.

here is my sa-exim run condition: SAEximRunCond: ${if and 
{{def:sender_host_address} {!eq {$sender_host_address}{172.16.206.143}} 
{!eq {$sender_host_address}{127.0.0.
1}}{!eq {$h_X-SA-Do-Not-Run:}{Yes}} } {1}{0}}SAEximRunCond: ${if and 
{{def:sender_host_address} {!eq {$sender_host_address}{172.16.206.143}} 
{!eq {$sender_host_address}{127.0.0.
1}}{!eq {$h_X-SA-Do-Not-Run:}{Yes}} } {1}{0}}

Here are a few lines from the log showing the action taken on a message 
it shouldn't scan.
2004-04-07 14:54:20 1BBJ7r-000Cee-5h SA: Action: scanned but message 
isn't spam: hits=-4.2 required=5.6 (scanned in 1/1 secs | Message-Id: 
[email protected]). From 
<[email protected]> (host=NULL [172.16.206.143]) for 
[email protected]

Does anyone have any idea why my sa-exim run condition isn't picking up 
the 172.16.206.143 address? 
Thanks much,
Tim Sexton