zabbix 1.4.4 Expressions in triggers can't begin with a number.

[zabbix_es]

I tried to add an trigger expression begining with a number and zabbix does not allow me.

For example:

Expression: 100-{item.value.last(0)}*20 ...


To avoid that error I had to put a '(' to enclose the expression:

(100-{item.value.lastt(0)}*20 ...)