Please post the NetFlow config from your switch.
Cisco 6509 switch
ip flow-cache timeout active 1
ip flow ingress layer2-switched vlan 701
mls netflow interface
mls flow ip interface-full
no mls flow ipv6
ip flow-export source Vlan701
ip flow-export version 5
ip flow-export destination 10.70.1.28 2055
ip address 10.70.1.1 255.255.248.0
ip flow ingress
ip flow egress
You might get some direction here: (page 5)
That looks right, although I'm not sure how NTA handles the data from the "ip flow ingress layer2-switched" command. Things to check:
1) Do you have data in your flow cache ("show ip cache flow")?
2) Does "show ip flow export" look like you are sending flow exports?
3) If you run a packet capture for UDP port 2055 on the NTA box, are you receiving flows?