I just installed zabbix 1.9.8 on Ubuntu 11.10. I want to test the low-level discovery of filesystems and network interfaces. I tried to create a new discovery rule for the Linux template as described in the manual (Zabbix 2.0: 12.3). I entered the keys vfs.fs.discovery or net.if.discovery. But whenever I hit the "Save" button, an error message displays, saying "Cannot add discovery rule" and "Incorrect arguments passed to function". There's no hint in the server log file what could be wrong.
Someone else on the forum has the same effect, so I opened this issue.