snmp item working before, now become "not supported"

[Ting-sf]

HI,

I have a snmp host and monitor one item, it was working good in last a month and so, today I discover it does not receive data anymore, and it shows "not supported" and "no such name in MIB file" error.

I do not know where to start to start trouble shoot, as far as I know, I did not do change configuration for this host. any help would be much appreciated.