c# - GridView row not updating, text from textbox in gridview edit template not coming -

i have grid view in want update row not happening. datasource datatable. please help.

below markup

<asp:gridview id="grdv" runat="server" autogeneratecolumns="false"       onrowediting="grdv_rowediting"  onrowupdating="grdv_rowupdating">   <columns>    <asp:templatefield headertext="clip description">         <itemtemplate>             <asp:label id="lbldescrptn" runat="server" text='<%# bind("description") %>'>             </asp:label>         </itemtemplate>         <edititemtemplate>             <asp:textbox id="desctbx" runat="server" text='<%# bind("description") %>'>             </asp:textbox>         </edititemtemplate>     </asp:templatefield>     <asp:commandfield showeditbutton="true" />   </columns> 

and code behind

    protected void grdv_rowupdating(object sender, gridviewupdateeventargs e)     {          // retrieve row being edited.       int index = grdv.editindex;         gridviewrow row = grdv.rows[index];                    textbox t1 = row.findcontrol("desctbx") textbox;          datatable dt = (datatable)session["tmdatatable"];          dt.rows[index]["description"] = t1.text; //description column of datatable         dt.acceptchanges();         grdv.editindex = -1;         grdv.datasource = dt;         grdv.databind();      } 

on debugging , find textbox passing empty string t1.text ="" after have filled textbox new values. think error in line

textbox t1 = row.findcontrol("desctbx") textbox; 

pageload code

    protected void page_load(object sender, eventargs e)     {          if (!ispostback)         {             grdv.datasource = session["tmdatatable"];             grdv.databind();         }           datatable finaldt = gettable();          grdv.datasource = finaldt;         grdv.databind();         session["tmdatatable"] = finaldt;      } 

alter code bit , check. change editindex e.rowindex

protected void grdv_rowupdating(object sender, gridviewupdateeventargs e) {     gridviewrow row = grdv.rows[e.rowindex]; // line changed           textbox t1 = row.findcontrol("desctbx") textbox;      datatable dt = (datatable)session["tmdatatable"];      dt.rows[row.dataitemindex]["description"] = t1.text; //description column of datatable     dt.acceptchanges();     grdv.editindex = -1;     grdv.datasource = dt;     grdv.databind(); } 

have done this:

protected void page_load(object sender, eventargs e) {          if(!ispostback)     {         grdv.datasource = session["tmdatatable"];         grdv.databind();     } }