second pool iRule for Maintenance page

I have attempted to create an iRule that moves traffic from one pool to a Maint-Page pool when the members of the Production pool are "down". Each server in the Production pool (prf1.aviallinc.com-ssl) has a Health Monitor which so when the health monitor reports the servers down the iRule should move traffic to the Maint-Pool (sorry_ssl).

But, nothing happens.

Local Traffic ›› iRules : iRule List ›› tst2-sorry_ssl Partition / PathCommon

when HTTP_REQUEST { if { [active_members "/Common/prf1.aviallinc.com"] < 1}{ pool "/Common/tst2-sorry.aviall.com-ssl" return } }

I feel certain I have failed with my syntax BTW: I have tried with and without "

BIG-IP 11.5.1 Build 5.0.147 Hotfix HF5 

Stan