c# - Gridview not appearing -

i somehow come strange error. gridview won't appear. here code - first .aspx markup:

<asp:gridview id="zakljucani" runat="server" autogeneratecolumns="false"      onrowcommand="zakljucani_rowcommand" pagesize="300" height="127px"      style=" visibility:visible; border-color:red" >     <columns>         <asp:boundfield datafield="korisnickoime" headertext="korisnicko ime" visible="true" />         <asp:boundfield datafield="mail" headertext="mail" visible="true" />         <asp:boundfield datafield="datumzakljucavanja"                  headertext="datum vrijeme zaključavanja" />         <asp:boundfield datafield="hourselapsed" headertext="protekli sati" />         <asp:templatefield headertext="otključaj">             <itemtemplate>                 <asp:button id="button1" commandargument='<%#eval("korisnickoime")%>'  runat="server" enabled='<%#convert.toint32(eval("hourselapsed"))>24%>' text="otključaj" />             </itemtemplate>         </asp:templatefield>     </columns> </asp:gridview> 

and code

 protected void page_load(object sender, eventargs e)  {      getdata();         }   private void getdata()  {      string cs = configurationmanager.connectionstrings["konekcija"].connectionstring;       using (sqlconnection con = new sqlconnection(cs))      {          sqlcommand cmd = new sqlcommand("spzakljucaniracuni", con);          cmd.commandtype = commandtype.storedprocedure;           con.open();           zakljucani.datasource = cmd.executereader();          zakljucani.databind();      } }  private void enableuseraccount(string username) {     string cs = configurationmanager.connectionstrings["konekcija"].connectionstring;      using (sqlconnection con = new sqlconnection(cs))     {         sqlcommand cmd = new sqlcommand("otkljucajzakljucaniracun", con);         cmd.commandtype = commandtype.storedprocedure;          sqlparameter paramusername = new sqlparameter()              {                 parametername = "@korisnickoime",                 value = username              };          cmd.parameters.add(paramusername);          con.open();         cmd.executenonquery();     } }  protected void zakljucani_rowcommand(object sender, gridviewcommandeventargs e) {     enableuseraccount(e.commandargument.tostring());     getdata(); } 

the problem gridview doesn't appear. today worked fine, , later not.

i don't know if there error, or problem when binding. hope find mistake if there one.

add sqldatareader

    sqldatareader dr;     dr = cmd.executereader();     zakljucani.datasource = dr;