trigger calculation

[mary nancy]

Hi all

Greeting,

This is my second post for the day...
I would like to know how triggers can be calculated using parameters.
for eg:-
if i want a trigger to find if the disk free space is less than 20% of the total disk space on a windows server.
how do i do it?

I tried this:
{windows074:diskfree[c:].last(0)}< 0.2 *{windows074:disktotal[c:].last(0)}

but this gave an error Unable to get value for functionid [11248]
can anybody help me with this?????????????


Regards
Nancy