diff --git a/app_config.js b/app_config.js
index 58a0e93..6e843fc 100644
--- a/app_config.js
+++ b/app_config.js
@@ -20,7 +20,7 @@ module.exports = {
   },
   rinkeby: {
     contract_addresses:{
-      'Conference': '0xDdDf97B54a515172AadD9590d5aBCE524683f390',
+      'Conference': null,
       'ConfirmationRepository': null
     },
     name: 'RINKEBY NET',
diff --git a/contracts/Conference.sol b/contracts/Conference.sol
index 0e34f66..69502c7 100644
--- a/contracts/Conference.sol
+++ b/contracts/Conference.sol
@@ -90,12 +90,12 @@ contract Conference is Destructible {
 		}
 	}
 
-	function registerWithEncryption(string _participant, string _encrypted) public payable onlyActive{
+	function registerWithEncryption(string _participant, string _encrypted) external payable onlyActive{
 		registerInternal(_participant);
 		RegisterEvent(msg.sender, _participant, _encrypted);
 	}
 
-	function register(string _participant) public payable onlyActive{
+	function register(string _participant) external payable onlyActive{
 		registerInternal(_participant);
 		RegisterEvent(msg.sender, _participant, '');
 	}
@@ -110,7 +110,7 @@ contract Conference is Destructible {
 		participants[msg.sender] = Participant(_participant, msg.sender, false, false);
 	}
 
-	function attendWithConfirmation(bytes32 _confirmation) public onlyActive{
+	function attendWithConfirmation(bytes32 _confirmation) external onlyActive{
 		require(isRegistered(msg.sender));
 		require(!isAttended(msg.sender));
 		require(confirmationRepository.claim(_confirmation, msg.sender));
@@ -120,7 +120,7 @@ contract Conference is Destructible {
 		AttendEvent(msg.sender);
 	}
 
-	function withdraw() public onlyEnded{
+	function withdraw() external onlyEnded{
 		require(payoutAmount > 0);
 		Participant participant = participants[msg.sender];
 		require(participant.addr == msg.sender);
@@ -128,7 +128,7 @@ contract Conference is Destructible {
 		require(participant.paid == false);
 
 		participant.paid = true;
-		assert(participant.addr.send(payoutAmount));
+		participant.addr.transfer(payoutAmount);
 		WithdrawEvent(msg.sender, payoutAmount);
 	}
 
@@ -137,7 +137,7 @@ contract Conference is Destructible {
 		return this.balance;
 	}
 
-	function confirmation() constant public returns (bool){
+	function confirmation() constant external returns (bool){
 		return address(confirmationRepository) != address(0);
 	}
 
@@ -160,14 +160,14 @@ contract Conference is Destructible {
 
 	/* Admin only functions */
 
-	function payback() public onlyOwner onlyActive{
+	function payback() external onlyOwner onlyActive{
 		payoutAmount = payout();
 		ended = true;
 		endedAt = now;
 		PaybackEvent(payoutAmount);
 	}
 
-	function cancel() public onlyOwner onlyActive{
+	function cancel() external onlyOwner onlyActive{
 		payoutAmount = deposit;
 		cancelled = true;
 		ended = true;
@@ -176,19 +176,20 @@ contract Conference is Destructible {
 	}
 
 	/* return the remaining of balance if there are any unclaimed after cooling period */
-	function clear() public onlyOwner onlyEnded{
+	function clear() external onlyOwner onlyEnded{
 		require(now > endedAt + coolingPeriod);
 		require(ended);
 		var leftOver = totalBalance();
-		require(owner.send(leftOver));
+		
+		owner.transfer(leftOver);
 		ClearEvent(owner, leftOver);
 	}
 
-	function setLimitOfParticipants(uint _limitOfParticipants) public onlyOwner onlyActive{
+	function setLimitOfParticipants(uint _limitOfParticipants) external onlyOwner onlyActive{
 		limitOfParticipants = _limitOfParticipants;
 	}
 
-	function attend(address[] _addresses) public onlyOwner onlyActive{
+	function attend(address[] _addresses) external onlyOwner onlyActive{
 		for(uint i=0;i<_addresses.length;i++){
 			var _addr = _addresses[i];
 			require(isRegistered(_addr));
diff --git a/truffle.js b/truffle.js
index 06b130f..b5a3c81 100644
--- a/truffle.js
+++ b/truffle.js
@@ -40,6 +40,7 @@ module.exports = {
       host: "localhost",
       network_id: 4,
       port: 8545,
+      from: "0xbfb142f5bc1d33b7e173acd77719375faf5c72c1", // default address to use for any transaction Truffle makes during migrations
       gasPrice: 50000000000 // 50 gwei,
     },
     ropsten: {