diff --git a/src/paheko.rs b/src/paheko.rs
index b8ee3dc..904fe2d 100644
--- a/src/paheko.rs
+++ b/src/paheko.rs
@@ -95,7 +95,7 @@ struct SimpleTransaction {
     amount: f64,
     credit_account_code: String, 
     debit_account_code: String,
-    reference: String,
+    reference: Option<String>,
     linked_users: Vec<Id>,
     linked_subscriptions: Vec<Id>,
     accounting_year: Id 
@@ -321,7 +321,7 @@ impl AuthentifiedClient {
             #[allow(dead_code)]
             id: u64,
             label: String,
-            reference: String,
+            reference: Option<String>,
             #[serde(deserialize_with = "deserialize_json_list")]
             accounts_codes: Vec<String>,
             year_id: u64,
@@ -545,9 +545,11 @@ impl AuthentifiedClient {
             .text("debit", transaction.debit_account_code)
             .text("credit", transaction.credit_account_code)
             // "Numéro pièce comptable" enregistré au niveau de la transaction
-            .text("reference", transaction.reference) 
         ;
 
+        if let Some(reference) = transaction.reference { 
+            form = form.text("reference", reference);
+        }
         for linked_id in transaction.linked_users {
             form = form.text("linked_users[]", format!("{}", linked_id.0));
         }
diff --git a/src/sync_helloasso.rs b/src/sync_helloasso.rs
index 615e008..b87d14f 100644
--- a/src/sync_helloasso.rs
+++ b/src/sync_helloasso.rs
@@ -30,7 +30,7 @@ async fn get_auth_client_from_cache(
         Ok(auth_client)
     }
 
-    eprintln!("Init HA client");
+    eprintln!("Initializing HA client…");
 
     match &user_cache.helloasso_session {
         Some(cached_session) => {
@@ -97,8 +97,6 @@ pub async fn sync_helloasso(
     user_cache: &mut UserCache,
     dry_run: bool
 ) -> Result<()> {
-
-    eprintln!("wow");
     let mut ha_client: helloasso::Client = helloasso::Client::new(helloasso::ClientConfig {
         base_url: Url::parse("https://api.helloasso.com/v5/")
                 .expect("Expected valid helloasso API base URL"),
diff --git a/src/sync_paheko.rs b/src/sync_paheko.rs
index be8e002..0f8b292 100644
--- a/src/sync_paheko.rs
+++ b/src/sync_paheko.rs
@@ -112,7 +112,7 @@ pub async fn sync_paheko(
 
         let existing_matching_transactions: Vec<&SimpleTransaction> = existing_transactions
             .iter()
-            .filter(|t| t.reference == answer.reference)
+            .filter(|t| t.reference == Some(answer.reference.clone()))
             .collect();
 
         // check for existing user in paheko by email
@@ -123,6 +123,7 @@ pub async fn sync_paheko(
         let pk_user_summary = match existing_user_opt.clone() {
             Some(user) => {
                 eprintln!(" Found existing paheko user by matching name.");
+                // TODO: if existing user is different, update the details of user
                 user
             },
             None => {
@@ -233,7 +234,7 @@ pub async fn sync_paheko(
                 // TODO: make the label template configurable
                 label: format!("{} {:?} via {}", pk_membership.service_name, pk_membership.mode_name, via_name),
                 amount: pk_membership.payed_amount,
-                reference: answer.reference.clone(),
+                reference: Some(answer.reference.clone()),
                 credit_account_code: "756".to_string(), // cotisations account
                 debit_account_code: debit_account_code.to_string(), // helloasso account
                 inception_time: answer.inception_time,
@@ -264,7 +265,7 @@ pub async fn sync_paheko(
                     }.id.clone(),
                     label: format!("Don lié à une adhésion via {}", via_name),
                     amount: answer.donation_amount,
-                    reference: answer.reference.clone(),
+                    reference: Some(answer.reference.clone()),
                     credit_account_code: DONATION_ACCOUNT_CODE.to_string(), // account  754 - Ressources liées à la générosité du public
                     debit_account_code: debit_account_code.to_string(), // compte d'encaissement
                     inception_time: answer.inception_time,