socket.handshake.session.keyname shows undefined - sockets

Question

I'm making a multiplayer game. below is the flow of the process when i get an error:
(1) After logging in the username is getting stored in session:
socket.on('login', function(username)
{
socket.handshake.session.username = username;
socket.handshake.session.save();
var afterLogin = '/groups';
socket.emit('afterLogin', afterLogin);
});
(2) User get redirect to another page and complete the game, after completing the game user send score and room id to the server:
var submitScore = { score: hit, room: 'gryffindor'};
socket.emit('submitScore', submitScore);
(3) Server get the score and room-id and iterate through all the client and decide the max score, get the username from the session, and send the winner name and score to all user:
socket.on('submitScore', function(submitScore)
{
var room = submitScore.room;
var score = submitScore.score;
if (room == "gryffindor")
{
gryfScoreArray[socket.handshake.session.username] = score;
checkGryfUser --;
if (checkGryfUser == 0)
{
var max = 0;
var winnerName;
for(var index in gryfScoreArray)
{
if (gryfScoreArray[index] > max)
{
max = gryfScoreArray[index];
winnerName = index;;
}
}
// console.log(socket.id);
var winner = {username: winnerName, maxScore: max}
io.in(room).emit('gryfWinner', winner);
// console.log(winner.username);
// console.log(winner.maxScore);
}
}
So, the problem is socket.handshake.session.username giving undefined in point point (3)