allow traffic to VS based on the source IP fwded in the http get request

I tried with the below irule , but this is not working as throwing me expections and command not valid

when HTTP_REQUEST{ if { [class match [[HTTP::header Client-IP]] eq "datagroup_QA" ] }{ Traffic is allowed. Client IP match found in datagroup_QA return } else { Traffic is dropped. Client IP match not found in datagroup_QA drop } }

If the IP from HTTP header matched the IP listed in datagroup , connection need to be allowed if not it need to be rejected.