asp.net - Mutiple list item selection from multiple Listbox in asp.net

Question

I have dynamic List boxes in my asp page. and I need to select the items from each list boxes for the below ex. selected item

[Date].[Calendar Date].[Calendar Year].&[2002] from one list box

[Date].[Calendar Date].[Calendar Semester].&[2002]&[2] from another list box

[Date].[Calendar Date].[Calendar Quarter].&[2001]&[4] from another etc....

I need to bring those above selected items as below

FROM ( SELECT { 
[Date].[Calendar Date].[Calendar Year].&[2002]
} ON COLUMNS 
FROM ( SELECT { 
[Date].[Calendar Date].[Calendar Semester].&[2002]&[2]
} ON COLUMNS 
FROM ( SELECT { 
[Date].[Calendar Date].[Calendar Quarter].&[2001]&[4]
} ON COLUMNS

below code that i used to do this but no Luck :)

    protected void imgRunReport_Click(object sender, ImageClickEventArgs e)
{
Panel tt = Cache["tt"] as Panel;
string mdxqry;
isRefresh = true;
string Cubename = ddlCubeList.SelectedItem.Value;


Dictionary<string, string> selectedfil = new Dictionary<string, string>();
foreach (ListBox ctl in tt.Controls.OfType<ListBox>())
{
string strSelectedFilters = string.Empty;
selectedfil.Remove(ctl.Text);

foreach (ListItem li in ctl.Items)
{

if (li.Selected)
selectedfil.Add(li.Text, li.Value);

}
strSelectedFilters = "FROM ( SELECT { " + string.Join("," , new List<string>(selectedfil.Values).ToArray()) + "}" + " ON COLUMNS ";



}

}

Remember: these values comes from dynamic listboxes

thanks In advance