Styles applied for PrintDataGrid are not getting affected.

Hi, I have used printDataGrid for printing my data. I have applied css style for the print datagrid. style applied for this printDataGrid is given below.

        mx|PrintDataGrid.printing {

            headerColors: #D8DCDD, #F1F2F2;

            color: #000000;   

            alternatingItemColors: #D2D3D4, #F1F2F2;

        }

Use of mx:PrintDataGrid  in my application:

<mx:PrintDataGrid id="ddDataGrid" width="99%" height="100%" styleName="printing" sizeToPage="true"/>

But in the print document not able get alternatingItemColors for the printed datagrid.