sql - ADO.Net c# 0x80131904 must declare scalar variable/function -

i'm trying use function via sql connection i've done everywhere else in application (only here give error, not rest of application). when searched error code meant responses found it's error when 1 can't connect sql server? doesn't give solution.

here c# code

 sqlconnection connection = database.getconnection();                  datatable dt = new datatable("crc");                 sqlcommand cmd = new sqlcommand("select dbo.calcrentalcharge(@rentalstartdatetime,@rentalenddatetime,@cartypeid)", connection);             try         {             connection.open();             using (sqldatareader dr = cmd.executereader())             {                 cmd.commandtype = commandtype.text;                 cmd.parameters.add("@rentalstartdatetimetext", sqldbtype.datetime).value = rentalstartdatetimebox.text;                 cmd.parameters.add("@rentalenddatetimetext", sqldbtype.datetime).value = rentalenddatetimebox.text;                 cmd.parameters.add("@cartypeidtext", sqldbtype.int).value = cartypeid.text;                  connection.open();                 decimal rentalchange = (decimal)cmd.executescalar();                 connection.close();                 messagebox.show("the rental change is: " + rentalchange.tostring());                  if (dr.hasrows)                 {                     dt.load(dr);                     datagridview1.datasource = dt;                 }             }             connection.close(); 

can me function work?

dont use cmd.executereader() before adding parameter command object give error add parameter command , cmd.execurereader()