sort event not being hit

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C#

I have developed a webpart SpGridview, but my sort and paging eventhandler are not being fired. when I click on the fields to sort, everything will go blank.

I have taken these three steps

1)

dtGridView.Sorting += new GridViewSortEventHandler(dtGridView_Sorting);

2)

void dtGridView_Sorting(object sender, GridViewSortEventArgs e) 
{
}
 
dtGridView.AllowSorting = true;

3)

SPBoundField boundField;
boundField = new SPBoundField();
boundField.HeaderText = "status"
boundField.DataField = "status"
boundField.SortExpression = "status"
dtGridView.Columns.Add(boundField);

Why I am not hitting debug point in the event sort? please help