keyword intergratedsecurity not supported

Question

 Hi I get the following error. when I try to connect to the SQl Server. The keyword IntergratedSecrity isn't supported. What did I do wrong ?

 

here is my class and method method to create a connectionstring.

 

using System.Configuration;
using System.Data.SqlClient;



namespace WindowsFormsApplication1.DataAccessLayer
{
    class DatabaseLayer
    {
        public static SqlConnection OpenConnection()
        {
            var connection = new SqlConnection(ConfigurationManager.ConnectionStrings["customers"].ConnectionString);
            connection.Open();
            return connection;

        }
    }

}

 and here is my ap.config

 

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
    </configSections>
      <connectionStrings>
            <add name="customers" connectionString="Data Source=\\MAC-CASPER\SQLSERVERCASPER; Initial Catalog=Customer_xxxxx; IntegratedSecurity=True" providerName="System.Data.SqlClient" />
      </connectionStrings>
</configuration>