iRule Editor can't find default_pool

Thanks for the tips and discussion guys, here's what I've ended up with at the moment, it passes the syntax checker at least ..

I've added a check for < 1 active member in the bot pool with a corresponding event disable to hop out of the rule if there are no active members in the bot pool.

Is there a better/more effecient way to compose this iRule?

  
 when CLIENT_ACCEPTED {   
 set default_pool [LB::server pool]   
 }   
 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 {  
 pool $default_pool  
 }  
 }