Dynamically increase the table row

Trying to increase the rows of a table dynamically, seems like the rows are increased and values assigned to the column. Able to verify these with the alert statement. But when form is rendered, no additional rows are displayed.

Used the following java script in the initialize event of the table.

Please let me why the newly added rows are not showing up.

RootForm.Page2.Table7::initialize -

var rowLength=xfa.resolveNodes("xfa.datasets.data.root.parentNode[*]").length;
//app.alert(rowLength);
for(var index=0; index < rowLength; index++){
//app.alert(index);
var oRowInstance=RootForm.Page2.Table7.resolveNode("Row1[" + index + "]");
oRowInstance.Cell1.rawValue="10";
oRowInstance.Cell2.rawValue=18;
//app.alert(oRowInstance.Cell1.rawValue);
//app.alert(oRowInstance.Cell2.rawValue);
oRowInstance.instanceManager.addInstance(true);
xfa.form.recalculate(true);

}

Thank you