irule access for defined IP/client

Hello,

I want to write an iRule to allow only one defined IP and one client-group access to one defined url.

My code looks like this:

when HTTP_REQUEST {

if { ([HTTP::host] equals "cname.sport.net")}{
           if { [class match [IP::client_addr] equals "datagroup-xxx"] or [class-match [IP::client_addr] equals "xxx.xxx.xxx.xxx"] }{
               pool sport-http-pool
               persist none
              }
   else {
       drop
       }
   }
}

I get this error: 01070151:3: Rule [/Common/irule-test-http] error: /Common/irule-test-http:4: error: [undefined procedure: class-match][class-match [IP::client_addr] equals "xxx.xxx.xxx.xxx"]

Can anybody help me?