packets sent on virtual IP don't hit iptables rule

Are you sure there is no matching rule in other tables, like mangle or nat ? You could also try to log every paquet coming in INPUT, or even better, try the TRACE target in raw table (PREROUTING chain), if that is available on RHEL 6

Edit (I can't add a comment yet) :

OK, so the packet hit the interface, but it's not considered as a one the should be treated locally. Check your routing table, maybe you don't have a scope link route to this network, or the packet is dropped by the kernel because of RPF filters (this could happen depending of the network topology) : check https://access.redhat.com/site/solutions/53031