bug: wrong SQL request and broken graphs in e-mail

[rudw0lf]

I established a told plug-in and configured a threshold for one of hosts. In logs I see such line:
CMDPHP: Poller[0] ERROR: SQL Assoc Failed!, Error:'1064', SQL:"select field_name,field_value from host_snmp_cache where host_id= and snmp_query_id= and snmp_index=''"
I receive on notification mail however in them the schedule isn't displayed, instead of it I see the reference to the nonexistent schedule:
http://cacti//graph.php?local_graph_id=0&rra_id=1 (cacti host = cacti )

In what there can be a problem?

Cacti Version: 0.8.7i, Plugin Architecture Version: 3.1 Told ver. 0.4.9-3