Sflow and Dell PowerConnect

Sflow and Dell PowerConnect

I want to get more insight in my network so I would like to enable the NetFlow plug-in in OpManager. 

I've installed the NetFlow plug-in on the OpManager server and it's listiging to port 9996. If I go to the NetFlow dashboard it says that there is no router configured to sent NetFlow packets to the NetFlow analyzer. 

SNTP clock synchonisation is enabled:

show clock

08:48:52 (UTC+1:00) Mar 24 2015
Time source is SNTP

SNMP is enabled as well:

show snmp

Community-String     Community-Access View Name        IP Address
-------------------- ---------------- ---------------- ----------------
*****                                 Read Only        Default          <opmanagerserver>


Community-String     Group Name                     IP Address
-------------------- ------------------------------ ----------------
*********                  DefaultRead                    All

Traps are enabled.
Authentication trap is enabled.

Sflow is configured as follow. Global command:

sflow 1 destination owner 1 timeout 4294966144
sflow 1 destination <OpmanagerServer> 9996

On the interface:
sflow 1 sampling 1024
sflow 1 polling 30


Any idea's?