Cisco ; Multicast

Please can you help.

I have enabled multicast on our network which seem to be working fine only to find out that workstations in the same vlan as the servers sending out traffic do not receive multicast.

What I have configured is the ff on the router:

ip pim send-rp-announce Vlan615 scope 16
ip pim send-rp-discovery scope 16

Then

no ip redirects
ip pim sparse-dense-mode
ip igmp version 1
ip cgmp

on each participating vlan

All other workstations in vlans such as 610, 611 and others receive multicast but not those in vlan 610 although these workstations receive multicast from servers in vlan 610.

Please why is this?

Thanks