problem with dhcp on 2960 switches

Hi All

I need your help

We have a dhcp server that was connected to Cisco 2960 which in turn was
connected to alcatel switches, all worked fine. we changed the alcatel
switches to cisco 2960's. We now have a problem that only devices directly
connected to the original 2960(where the dhcp server is connected to) is
receiving IP addresses we have now 4 other 2960's onthe network but we
cannot get a IP address when we connect to any of the ports. doing a sniffer
trace on the working switch the DHCP four way handshake is performed,
discovery>>offer>>request>>>ack

On one of the other switches only the discovery is seen but no offer
response from the dhcp server is seen therefore no ip address is received.
the new switches only have portfast set and an ip address for vlan1 so I
cannot understand what is stopping the dhcp traffic

Any  Ideas

Thanks

Simon