I have a grid with following parameters:
<grid id="filterGrid" mold="paging" pageSize="20" >

If I want to set rows to invisible such that visible rows are less than pageSize (20 in this case) I get following error: "Failed to process outer f is undefined"
Any guidance ? Is this a bug ?

example:
int maxRows=filterGrid.getRows().getChildren().size();
for(int k=0; k < maxRows; k++){
Row cRow=(Row)filterGrid.getRows().getChildren().get(k);
if(k<(maxRows-5)){ //this means only 5 rows will be visible , any number below 20 throws the error
System.out.println("Checking row visible :"+k+cRow.isVisible());
cRow.setVisible(false);
}
}