irule matchclass not working for networks

I am having a problem with matchclass identifying that a host is in a address class containing networks.

 

 

It works it the class just contains hosts addresses

 

 

classes defined

 

 

class cl_net_London {

 

network 10.64.0.1/18

 

}

 

 

class cl_dctm_dev_net_Marc {

 

host 10.64.38.97

 

}

 

 

Irule extract

 

 

when CLIENT_ACCEPTED {

 

if { [matchclass [IP::client_addr] equals $::cl_net_London] }{

 

log local0. "client [IP::client_addr] with class: $::cl_net_London"

 

snat 10.64.27.75

 

} else {

 

log local0. "client [IP::client_addr] no matches"

 

snat 10.64.27.85

 

}

 

}

 

 

Extract from log

 

Rule ir_dctm_sta_web_network : client 10.64.38.97 no matches

 

 

Matchclass works when matching a host address not a network

 

if { [matchclass [IP::client_addr] equals $::cl_dctm_dev_net_Marc] }

 

 

Any ideas everything I have read says matchclass should be able to check if an ip-address matches a group of networks.