diff --git a/ibc_module.go b/ibc_module.go
index 192f846..93daccb 100644
--- a/ibc_module.go
+++ b/ibc_module.go
@@ -1,7 +1,6 @@
 package nfttransfer
 
 import (
-	"fmt"
 	"math"
 	"strings"
 
@@ -236,7 +235,7 @@ func (im IBCModule) OnAcknowledgementPacket(
 			sdk.NewAttribute(types.AttributeKeyReceiver, data.Receiver),
 			sdk.NewAttribute(types.AttributeKeyClassID, data.ClassId),
 			sdk.NewAttribute(types.AttributeKeyTokenIDs, strings.Join(data.TokenIds, ",")),
-			sdk.NewAttribute(types.AttributeKeyAckSuccess, fmt.Sprintf("%t", ack.Success())),
+			sdk.NewAttribute(types.AttributeKeyAck, ack.String()),
 		),
 	)
 
diff --git a/keeper/grpc_query.go b/keeper/grpc_query.go
index d2daa10..d510246 100644
--- a/keeper/grpc_query.go
+++ b/keeper/grpc_query.go
@@ -27,7 +27,7 @@ func (k Keeper) ClassTrace(c context.Context,
 
 	hash, err := types.ParseHexHash(strings.TrimPrefix(req.Hash, "ibc/"))
 	if err != nil {
-		return nil, status.Error(codes.InvalidArgument, fmt.Sprintf("invalid denom trace hash: %s, error: %s", hash.String(), err))
+		return nil, status.Error(codes.InvalidArgument, fmt.Sprintf("invalid denom trace hash: %s, error: %s", req.Hash, err))
 	}
 
 	ctx := sdk.UnwrapSDKContext(c)
diff --git a/keeper/relay.go b/keeper/relay.go
index acdb32a..5c51f66 100644
--- a/keeper/relay.go
+++ b/keeper/relay.go
@@ -179,8 +179,8 @@ func (k Keeper) refundPacketToken(ctx sdk.Context, packet channeltypes.Packet, d
 		return err
 	}
 	if types.IsAwayFromOrigin(packet.GetSourcePort(), packet.GetSourceChannel(), data.ClassId) {
-		for _, tokenID := range data.TokenIds {
-			if err := k.nftKeeper.Transfer(ctx, voucherClassID, tokenID, "", sender); err != nil {
+		for i, tokenID := range data.TokenIds {
+			if err := k.nftKeeper.Transfer(ctx, voucherClassID, tokenID, types.GetIfExist(i, data.TokenData), sender); err != nil {
 				return err
 			}
 		}
@@ -260,7 +260,7 @@ func (k Keeper) createOutgoingPacket(ctx sdk.Context,
 		if isAwayFromOrigin {
 			// create the escrow address for the tokens
 			escrowAddress := types.GetEscrowAddress(sourcePort, sourceChannel)
-			if err := k.nftKeeper.Transfer(ctx, classID, tokenID, "", escrowAddress); err != nil {
+			if err := k.nftKeeper.Transfer(ctx, classID, tokenID, nft.GetData(), escrowAddress); err != nil {
 				return channeltypes.Packet{}, err
 			}
 		} else {
diff --git a/types/events.go b/types/events.go
index 146adaa..5d413ab 100644
--- a/types/events.go
+++ b/types/events.go
@@ -12,6 +12,7 @@ const (
 	AttributeKeyReceiver   = "receiver"
 	AttributeKeyClassID    = "classID"
 	AttributeKeyTokenIDs   = "tokenIDs"
+	AttributeKeyAck        = "acknowledgement"
 	AttributeKeyAckSuccess = "success"
 	AttributeKeyAckError   = "error"
 	AttributeKeyTraceHash  = "trace_hash"
diff --git a/types/trace.go b/types/trace.go
index d3d1cfb..3a4fdec 100644
--- a/types/trace.go
+++ b/types/trace.go
@@ -17,16 +17,15 @@ import (
 
 // ParseHexHash parses a hex hash in string format to bytes and validates its correctness.
 func ParseHexHash(hexHash string) (tmbytes.HexBytes, error) {
+	if strings.TrimSpace(hexHash) == "" {
+		return nil, fmt.Errorf("empty hex hash")
+	}
 	hash, err := hex.DecodeString(hexHash)
 	if err != nil {
 		return nil, err
 	}
 
-	if err := tmtypes.ValidateHash(hash); err != nil {
-		return nil, err
-	}
-
-	return hash, nil
+	return hash, tmtypes.ValidateHash(hash)
 }
 
 // GetClassPrefix returns the receiving class prefix