Problem with HTTP_RESPONSE for a certain host or pool

I'm trying to filter the HTTP_RESPONSE to only work with a certain host or pool. I'm getting an error saying "[HTTP::host] cannot be used with HTTP_RESPONSE". My question is how can I filter this iRule to only work with a certain host or pool? Thank you for your time... I'm a newbie!

version 10.2.2

when HTTP_RESPONSE {

if {[HTTP::host] contains "test.nowhere.com"}{

if {[matchclass [HTTP::header Content-Type] equals $::pdf_reports]}{

HTTP::header replace Cache-Control "max-age = 60"

}

}

}