Netflow/Flexible Netflow

I have Flexible Netflow configured on a Cisco ASR-920 and though I am able to see the device on the Realtime NetFlow Analyzer, I am not able to collect the NetFlow data.  When I try, I get the error message below.  The result is the same whether I use Netflow or Flexible Netflow.

Here's my config:

flow exporter DELTA_FLOW
description NetFlow Study
destination 10.x.x.x
source GigabitEthernet0/0/0
transport udp 2055
export-protocol netflow-v5

interface GigabitEthernet0/0/0
description Uplink to Core
mtu 1580
ip address 10.x.x.x 255.255.255.252
ip mtu 1562
ip pim sparse-mode
ip ospf 1 area 0
negotiation auto
cdp enable
no cdp tlv app
mpls ip
mpls label protocol ldp

And I also added this command but it had no effect:

ip flow-export source Loopback1

I had previously tried Netflow with this config:

ip flow-export destination 10.x.x.x 2055
ip flow-export version 5

interface GigabitEthernet0/0/0
description Uplink to Core
mtu 1580
ip flow ingress
ip address 10.x.x.x 255.255.255.252
ip mtu 1562
ip pim sparse-mode
ip ospf 1 area 0
negotiation auto
cdp enable
no cdp tlv app
mpls ip
mpls label protocol ldp

Any help would be greatly appreciated.