jQuery Grid Plugin - jqGrid

Hello All,

I created a JQGrid and i want to use the altRows property which create a "zebra" effect on the grid rows.

I wrote the code bellow:

 $('#tblParams').jqGrid({
datatype: 'local',
height: 400,
width: 740,
colNames: [
'ParamID', '’˜ÂŠ', '‘…‚ š’˜‰“', '’˜‰‹„'],
colModel: [
{ name:
'ParamID', index: 'ParamID', width: 90, key: true, resizable: false, hidden: true},
name:
'ParamName', index: 'ParamName', width: 90, resizable: false},
{ name:
'ParamValue', index: 'ParamValue', width: 90, key: true, resizable: false},
{ name:
'Edit', index: 'Edit', width: 50, resizable: false, formatter: 'link'}],
imgpath: '../JS/jqGrid/themes/iPost/images',

viewrecords: false,
onCellSelect: function(rowid, iCol, cellcontent)
{}
});

As you can see in the mark line i wrote  altRows: true
but my grid is not change and all the lines are with the same color.

Can someone help me please with this problem?

Thanks.