not able to connect at this ip address

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C#

ASP.NET

i have used this code to connect with my friends postgresql data base with their ip 192.168.1.13 but while connecting show not able to connect at this 192.168.1.13 address ............ but if i use "Server=127.0.0.1;Port=5432;Database=fastek;User Id=postgres;Password=atul;";
as a connection string it connect to my database successfully.... plz tell me if any other properties are required for postgresql connection.below my code is given

string connectionString = "Server=192.168.1.13;Port=5432;Database=CRM;User Id=postgres;Password=jeetsingh;Integrated Security=true;";
                System.Data.IDbConnection dbcon;
                dbcon = new NpgsqlConnection(connectionString);
                dbcon.Open();
                System.Data.IDbCommand dbcmd = dbcon.CreateCommand();
                string sql =  "select table_name from information_schema.tables where table_schema NOT IN ('pg_catalog', 'information_schema');";
                dbcmd.CommandText = sql;
                System.Data.IDataReader reader = dbcmd.ExecuteReader();
                DropDownList3.DataSource = reader;
                DropDownList3.DataValueField = "table_name";
                DropDownList3.DataTextField = "table_name";
                DropDownList3.DataBind();
                reader.Close();
                reader = null;
                dbcmd.Dispose();
                dbcmd = null;
                dbcon.Close();
                dbcon = null;