asp.net - [System.NullReferenceException: Object reference not set to an instance of an object.] -

i trying select user default_information.aspx.cs page , display user information on registration.aspx page created registration form.

i getting system.nullreferenceexception:object reference not set instance of object error. please me. i've given main part of it. debugged it. found every data selected db in string strusername,strpassword. code breaks on usernametxt.text = strusername; when try show username or password on text field.

default_information contains

    protected void gridviewprofile_selectedindexchanged(object sender, eventargs e)     {         registration objdef = new registration();         string username = gridviewprofile.rows[gridviewprofile.selectedindex].cells[1].text;         objdef.displayuser(username);     }     protected void update_click(object sender, eventargs e)     {         response.redirect("registration.aspx");     } 

registration.aspx contains

    protected void register_click(object sender, eventargs e)     {         user objuser = new user();         objuser.username = usernametxt.text;         objuser.password = passwordtxt.text;         objuser.email = emailtxt.text;         objuser.save();     }     public void displayuser(string username)      {   user obj = new user();         dataset objdataset = obj.profile(username);         string strusername = objdataset.tables[0].rows[0][0].tostring();         string strpassword = objdataset.tables[0].rows[0][1].tostring();         string stremail = objdataset.tables[0].rows[0][2].tostring();               usernametxt.text = strusername;         passwordtxt.text = strpassword;         emailtxt.text = stremail;                 } 

user class contains

public class user {         public void save()     {         clssqlserver obj = new clssqlserver();         obj.insertuser_info(username,password,email);                                }      public dataset profile(string username)     {         clssqlserver obj = new clssqlserver();         return obj.getalluser_info(username);     }  } 

clssqlserver contains

    public dataset getalluser_info(string username)     {         string connectionstring = "data source=localhost\\mssql;initial catalog=blooddb;integrated security=true";         sqlconnection objconnection = new sqlconnection(connectionstring);         objconnection.open();         string command = "select * login_donor username='" + username + "' ";         sqlcommand objcommand = new sqlcommand(command, objconnection);         dataset objdataset = new dataset();         sqldataadapter objadapter = new sqldataadapter(objcommand);         objadapter.fill(objdataset);         objconnection.close();         return objdataset;     }     public bool insertuser_info(string username,string password,string email)        {     string connectionstring = "data source=localhost\\mssql;initial catalog=blooddb;integrated security=true";             sqlconnection objconnection = new sqlconnection(connectionstring);             objconnection.open();             string strinsertcommand = "insert login_donor values('"+ username +"','"+ password + "','"+email+"')";             sqlcommand objcommand = new sqlcommand(strinsertcommand, objconnection);             objcommand.executenonquery();             objconnection.close();             return true;      } 

it looks using asp.net create user wizard control.because controls buried inside container, have rewarded after little excavation..lets start digging......

using wizard accessible locate text box

textbox  usernametxt= (textbox)createuserwizard.findcontrol("usernametxt"); usernametxt.text = strusername; 

hope help.