[Xymon] Devmon tests clear but snmpwalk works

Hi all

I know this is the Xymon list not Devmon but I think I'll have most luck on this list so apologies in advance.

I have a few of Cisco switches that I've just started monitoring at a couple of remote sites. snmpwalk works from the Xymon server but the Devmon tests are all clear (Devmon runs on the Xymon server).

When I look at the devmon.log I just see lots of

[16-05-26 at 20:19:09] No SNMP data found for ifName on swi02 [16-05-26 at 20:19:09] No SNMP data found for ifOutPktsSec on swi02 [16-05-26 at 20:19:09] No SNMP data found for ifOutCollisions on swi02

Any ideas on tracking this down?

We have many if these switches at other sites and they display correctly in Xymon.

Thanks

CC