c# - show selected value from grid view row using check box asp.net -

is there wrong in code? want show value of row 8 in gridview. have code , not working out me. no errors not show value expecting see.

protected void button1_click(object sender, eventargs e)     {         string str = string.empty;         string strname = string.empty;         foreach (gridviewrow gvrow in gridview1.rows)         {             checkbox chk = (checkbox)gvrow.findcontrol("chkrow");             if (chk != null & chk.checked)             {                 str += gridview1.datakeys[gvrow.rowindex].value.tostring() + ',';                 strname += gvrow.cells[8].text + ',';              }         }         strname = strname.trim(",".tochararray());         lblrecord.text = "<b>credit request: </b>" + strname;     } 

tried debug it. not getting cell value @ all. missing here?

updated output

update!:

manged make work. masterpage cause why not working. here code:

protected void btmdisplay_click(object sender, eventargs e)     {         //string data = "";         foreach (gridviewrow row in gridview1.rows)         {             if (row.rowtype == datacontrolrowtype.datarow)             {                 checkbox chkrow = (row.cells[0].findcontrol("chkctrl") checkbox);                 if (chkrow.checked)                 {                     using (sqlconnection scn = new sqlconnection("data source = 'paulo'; initial catalog=shoppingcartdb;integrated security =true"))                     {                         scn.open();                         sqlcommand cmd = new sqlcommand(@"update userdata set creditrequest = cast(replace(c.creditrequest, ',', '') int) creditrequests c inner join userdata u on c.username=u.username c.username=@username", scn);                         cmd.parameters.add("@username", sqldbtype.nvarchar).value = session["new"];                          cmd.executenonquery();                     }                 }             }         }         lblmsg.text = "approved"; 

what want happen when checkbox clicked, row(specifically row8) updated on sql database. have tried code above giving me error:

the parameterized query '(@username nvarchar(4000))update userdata set creditrequest = ca' expects parameter '@username', not supplied.

debug update:

debug

update 2:

i tried having this

sqlcommand cmd = new sqlcommand("update userdata set creditrequest = '" + row.cells[8].text + "' username=@username", scn);                         cmd.parameters.add("@username", sqldbtype.nvarchar).value = row.cells[1].text; 

and error conversion failed when converting varchar value '5,000

if binding gridview on page_load make sure have set if(!ispostback)

if(!ispostback) { //bindgridview here } 

try this

cmd.parameters.addwithvalue("@username", session["new"].tostring()); 

update

remove single qoutes around value of creditrequest

sqlcommand cmd = new sqlcommand("update userdata set creditrequest = " + row.cells[8].text + " username=@username", scn);