error in system.collections.generic.idictionary

public abstract class ConnectionProvider : IConnectionProvider, IDisposable
   {
       private string connString;
       private IDriver driver;
       private bool _isAlreadyDisposed;

       protected virtual string ConnectionString
       {
           get
           {
               return this.connString;
           }
       }

       public IDriver Driver
       {
           get
           {
               return this.driver;
           }
       }

       static ConnectionProvider()
       {
       }

       ~ConnectionProvider()
       {
           this.Dispose(false);
       }

       public virtual void CloseConnection(IDbConnection conn)
       {
           try
           {
               conn.Close();
           }
           catch (Exception ex)
           {
               throw new ADOException("Could not close " + conn.GetType().ToString() + " connection", ex);
           }
       }

       public virtual void Configure(IDictionary settings)
       {
           this.connString = settings[(object)"hibernate.connection.connection_string"] as string;
           if (this.connString == null)
               this.connString = this.GetNamedConnectionString(settings);
           if (this.connString == null)
               throw new HibernateException("Could not find connection string setting (set hibernate.connection.connection_string or hibernate.connection.connection_string_name property)");
           this.ConfigureDriver(settings);
       }

       protected virtual string GetNamedConnectionString(IDictionary settings)
       {
           string index = settings[(object)"hibernate.connection.connection_string_name"] as string;
           if (index == null)
               return (string)null;
             ConnectionStringSettings connectionStringSettings = ConfigurationManager.ConnectionStrings[index];
           if (connectionStringSettings == null)
               throw new HibernateException(string.Format("Could not find named connection string {0}", (object)index));
           else
               return connectionStringSettings.ConnectionString;
       }

       protected virtual void ConfigureDriver(IDictionary settings)
       {
           string name = settings[(object)"hibernate.connection.driver_class"] as string;
           if (name == null)
               throw new HibernateException("The hibernate.connection.driver_class must be specified in the NHibernate configuration section.");
           try
           {
               this.driver = (IDriver)Activator.CreateInstance(ReflectHelper.ClassForName(name));
               this.driver.Configure(settings); // error in these line
           }
           catch (Exception ex)
           {
               throw new HibernateException("Could not create the driver from " + name + ".", ex);
           }
       }

       public abstract IDbConnection GetConnection();

       public void Dispose()
       {
           this.Dispose(true);
       }

       protected virtual void Dispose(bool isDisposing)
       {
           if (this._isAlreadyDisposed)
               return;
           if (isDisposing)
           this._isAlreadyDisposed = true;
           GC.SuppressFinalize((object)this);
       }
   }