c# - RowUpdating Event of Gridview is not working properly -

i wanted update table through gridview. [visual studio 2010]

for have done following:

gridview>> editcolumns >> commandfield >> edit,update,cancel added grid.

gridview>> edittemplates >> added textbox names "textbox1">>end editing template.

row editing event:

public int i; protected void gv_rowediting(object sender, gridviewediteventargs e) {    i=gv.editindex = e.neweditindex; } 

row updating event:

protected void gv_rowupdating(object sender, gridviewupdateeventargs e)         {             try             {                 textbox txtsymbol;                  txtsymbol = ((textbox)(gv.rows[e.rowindex].cells[3].findcontrol("textbox1")));                  con.open();                 cmd = new sqlcommand("update temp set symbol=@symbol", con);                 cmd.parameters.addwithvalue("@symbol",txtsymbol.text);                 cmd.executenonquery();                 con.close();             }             catch (exception ex)             {             }         } 

i refered code here.

here mentioned th line should this:

txtsymbol = ((textbox)(gv.rows[e.rowindex].cells[3].findcontrol("textbox1")));

all coded thing not working.

`((textbox)(gv.rows[e.rowindex].cells[3].findcontrol("textbox1")))`  

is having null value.

gives exception in row updating event "null referance exception."

what wrong in code?

where making mistake.

please guid me.

protected void gv_rowediting(object sender, gridviewediteventargs e) {    gv.editindex = e.neweditindex;    bindgridview();//you have   bind gridview again here... } 

if dont bind gridview again after setiing edit index control not bounded gridview.thats why giving null refrence exception.