iRule Editor can't find default_pool

Actually, I'd like to use this one more, as I don't need to worry about health monitoring the default pool from the iRule, and don't need the default_pool variable.

I want this iRule to run only if a bot user-agent comes along, thoughts?

   
 when HTTP_REQUEST {   
 if { [active_members p_PUB_botfarm] < 1 } {   
 event disable   
 }   
 elseif { [matchclass [string tolower [HTTP::header User-Agent]] contains $::bots] } {   
 pool p_PUB_botfarm   
 } else {   
 event disable   
 }   
 }