Binding Souce not getting filter

BindingSource bs=new BindingSource();
List<items> lstItems= ListItems();
bs.DataSource=lstItems;
//I bind this bindingsouce to a gridview.
grd.DaataSource=bs;
//Then I copy this original BindingSource to a separate BindngSource
BindingSource filterBs=new BindingSource();
//Then I use a filter condition to Bindingsource
filterBs.Filter= "ItemCode='1' and cost>'200'";
grd.DataSource=null;
//Re binding the datasouce of the grid to the filtered bindingsource.
grd.DataSource=filterBs;</items>