C# - Selectedindexchanged On Dynamically Created Gridview?

I've created a gridview dynamically, now i want to fire an event when the selectedindex has changed.

GridView NewDg = new GridView();
NewDg.ID = "SubGridView" + e.Row.RowIndex.ToString();
NewDg.DataKeyNames = new string[]{"logentry_id"};
NewDg.SelectedIndexChanged += new EventHandler(NewDg_SelectedIndexChanged);
NewDg.RowDataBound += new GridViewRowEventHandler(NewDg_RowDataBound);

The RowDataBound works but it doesn't produce the right postback URL i guess.
In the RowDataBound i have the following code:

GridView sendingGridView = (GridView)sender;
e.Row.Attributes["onclick"] = ClientScript.GetPostBackClientHyperlink(sendingGridView, "Select$" + e.Row.RowIndex);

this produces the following code:

javascript:__doPostBack('SubGridView4','Select$0')

Only this doesn't lead to the postback to this function:

void NewDg_SelectedIndexChanged(object sender, EventArgs e)
{
GridView sendingGridView = (GridView)sender;
ViewDetails(Convert.ToInt32(sendingGridView.SelectedDataKey["logentry_id"].ToString()));
}