retrive connection string from app.config file

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C#

C#4.0

Sir,

I have problem in retrieving connectionstring from app.config file. I use the code
c# code

this.constring = ConfigurationManager.ConnectionStrings["CountryConstring"].ConnectionString;

//config file
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  
  <connectionStrings>
    <clear/>
     <add name="sConstring"
     providerName="System.Data.SqlClient"
     connectionString="Data Source=Dnyan-PC;Initial Catalog=DB_REGISTRATION;Integrated Security=True" />
  </connectionStrings>

</configuration>

but above not work in .net4 for window application
please help if any

thanx,
[Email Removed]
dnyaneshwar

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