In winforms you shouldn't need to create a new instnace of the grid. Simply drag and drop it onto the form or panel. The other thing is that the DataSource is any object that implements IEnumerable. This includes but is not limited to the List<T> collection, DataSet, DataTable, etc.
SriRamaKrishna is correct though, if this is an ASP.Net application, you should call the DataBind() method of the display_grid object as well. however, i would not recommend calling the Page.DataBind() method as that will persist to all controls on the page and would likely be an unneeded performance hit.
Hope this helps,
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