Help with Invalid Parameter Error

[xcenai]

I'm trying to calculate ink percentage levels for our printers in a custom template

I have two items:

• ItemA : inkMax
• itemB: inkNow

formula I use to calculate ink level is:
(last(inkNow) / inkMax ) * 100

But I keep getting incorrect expression errors

[cyber]

https://www.zabbix.com/documentation/current/en/manual/config/items/itemtypes/calculated

Example 1

Calculating percentage of free disk space on '/'.
Use of function last:

100*last(//vfs.fs.size[/,free])/last(//vfs.fs.size[/,total])
Zabbix will take the latest values for free and total disk spaces and calculate percentage according to the given formula.


last(//inkNow)/last(//inkMax)*100