asp.net Gridview not Binding

Question

well i need an urgent help, i m binding a gridview with cache,  & after this i need to search data through check boxes selection

 

pageload -

 

grvCollSearch.DataSource = (DataTable)Cache["lst1"];
grvCollSearch.DataBind(); 

 

 

wat happening is wen i select a check box i m filtering rows like

 

if(checked)

{

dt = (DataTable)Cache["lst1"]; 

dv.RowFilter = "GrandTotal < 300000";

grvCollSearch.DataSource = null;
grvCollSearch.DataSource = dv;
grvCollSearch.DataBind(); 

}

 else
{
dt = (DataTable)Cache["lst1"];
lblTotalCount.Text = dt.Rows.Count.ToString();

grvCollSearch.DataSource = dt;
grvCollSearch.DataBind();

}

 

 

 

but wen else part runs gridview is not binding it is showing previous result,why???????