Problem with JSONPath and preprocessing

[schrobbl]

Hello,

I am get some data via an ITEM x to my ZABBIX Server:
{"data":[
{
"zonename":"total",
"cpuused":1.23,
"cpuusedp":5.16,
"physmemused":84427094016,
"physmemusedp":81.91,
"virtmemused":89590183936,
"physmemusedp":85.14
},
{
"zonename":"system",
"cpuused":0.13,
"cpuusedp":0.55,
"physmemused":39016638464,
"physmemusedp":37.85,
"virtmemused":40151357440,
"physmemusedp":38.16
}]}

When I define another item with dependent on item x I cannot extract some value:
Preprocessing->JSONPath->$.[?(@.zonename == 'system')].cpuused
I always get an error like:
"cannot extract value from json by path "$.[?(@.zonename == 'system')].cpuused": object not found in jsonpath segment 1"

What I am doing wrong?

Regards
Schrobbl