Calculated Item not working correctly

[dlitman]

Hi There,

I'm running zabbix server 2.2.9. I have an issue where I have a boolean calculated item (wsb.target_changed) with a diff function to determine whether a text trapper item (wsb.target_label) has changed. Every so often I get a case where the text value changes however the calculated item using the diff function does not record a 1.

History from text item (wsb.target_label):
2015.Jul.24 18:00:16 BARBICA 2015_01_16 17:40 Disk_04
2015.Jul.24 17:45:20 BARBICA 2015_01_16 17:40 Disk_04
2015.Jul.24 17:30:13 BARBICA 2015_01_16 17:40 Disk_04
2015.Jul.24 17:29:52 BARBICA 2015_01_16 17:40 Disk_04
2015.Jul.24 17:00:16 BARBICA 2014_11_14 16:02 Disk_03
2015.Jul.24 16:45:16 BARBICA 2014_11_14 16:02 Disk_03
2015.Jul.24 16:30:14 BARBICA 2014_11_14 16:02 Disk_03
2015.Jul.24 16:15:16 BARBICA 2014_11_14 16:02 Disk_03


History from calculated item (wsb.target_changed):
2015.Jul.24 17:49:54 0
2015.Jul.24 17:44:54 0
2015.Jul.24 17:39:54 0
2015.Jul.24 17:34:54 0
2015.Jul.24 17:29:54 0
2015.Jul.24 17:24:54 0
2015.Jul.24 17:19:54 0
2015.Jul.24 17:14:54 0
2015.Jul.24 17:09:54 0
2015.Jul.24 17:04:54 0
2015.Jul.24 16:59:54 0
2015.Jul.24 16:54:54 0
2015.Jul.24 16:49:54 0
2015.Jul.24 16:44:54 0
2015.Jul.24 16:39:54 0
2015.Jul.24 16:34:54 0
2015.Jul.24 16:29:54 0
2015.Jul.24 16:24:54 0


Calculated item formula (wsb.target_changed):
diff("wsb.target_label")

Does anyone have any suggestions as to how I could begin troubleshooting this, or whether this is a likely bug.

Many thanks