Merging and grouping libraries code problem - sharepoint-2010

Question

I'm writing C# code to merge multiple libraries within a site collection and applying grouping on them. But grouping doesn't include documents from other sites regardless all share same meta data. Below, Blue box docs are from one site and green box docs are from other site and they don't group together.
Here are my code ,
DataTable dt = new DataTable();
DataRow dr;
DataColumn dc;
SPSite curSite = SPContext.Current.Site;
SPWebCollection subSites = curSite.AllWebs;
dc = new DataColumn("Title", Type.GetType("System.String"));
dt.Columns.Add(dc);
dc = new DataColumn("ReferenceNo", Type.GetType("System.String"));
dt.Columns.Add(dc);
dc = new DataColumn("Domain", Type.GetType("System.String"));
dt.Columns.Add(dc);
dc = new DataColumn("Created", Type.GetType("System.DateTime"));
dt.Columns.Add(dc);
for (int i = 0; i < subSites.Count; i++)
{
SPListCollection lists = subSites[i].Lists;
foreach (SPList list in lists)
{
if (list.Title == "Published Documents")
{
SPQuery myquery = new SPQuery();
//myquery.Query = "<GroupBy><FieldRef Name='Domain' /></GroupBy><OrderBy><FieldRef Name='Created' Ascending='False' /></OrderBy>";
myquery.Query = "<GroupBy><FieldRef Name='Domain' /></GroupBy>";
SPListItemCollection items = list.GetItems(myquery);
foreach (SPListItem item in items)
{
if (item != null)
{
dr = dt.NewRow();
dr["Title"] = item["Title"];
dr["ReferenceNo"] = item["ReferenceNo"];
dr["Domain"] = item["Domain"];
dr["Created"] = item["Created"];
dt.Rows.Add(dr);
}
}
}
}
}
//dt.DefaultView.Sort = "Created DESC";
spGridView.AllowGrouping = true;
spGridView.AllowGroupCollapse = true;
spGridView.GroupField = "Domain";
spGridView.DataSource = dt;
spGridView.DataBind();
Updates:: , Sorting Data Table with Domain fixed the issue..
**dt.DefaultView.Sort = "Domain";**

Answer 1

Rishi's answer:
Sorting Data Table with Domain fixed the issue..
dt.DefaultView.Sort = "Domain";
naveed's comment:
Perfect it worked for me. all goes well just we need to have
dt.DefaultView.Sort = "Your Sorting Attribute";