Several trigger functions accept an argument in two forms:
number : number of seconds
#num : number of items
Macros can be used with first type of parameter but not with teh second one:
{test:icmpping.max({$NITEMS})}=1 => OK
{test:icmpping.max(#{$NITEMS})}=1 => Error message : {$NITEMS} is not a float or counter or macro for function (max)