diff --git a/admin/setup_mvp.php b/admin/setup_mvp.php
index 4bbc699..cb6c626 100644
--- a/admin/setup_mvp.php
+++ b/admin/setup_mvp.php
@@ -38,16 +38,32 @@ $form = new Form($db);
 $action = GETPOST('action', 'alpha');
 if ($action == 'update_mappings') {
     $ca3_definitions = $config->getCA3LineDefinitions();
+    $updated_count = 0;
+    $debug_info = array();
     
     foreach ($ca3_definitions as $line => $definition) {
         $account_codes = GETPOST('account_codes_' . $line, 'array');
+        $debug_info[] = "Line $line: " . (is_array($account_codes) ? implode(',', $account_codes) : 'empty');
         
-        if (!empty($account_codes)) {
-            $config->updateAccountMapping($line, $account_codes);
+        // Process all lines, even empty ones (to clear mappings)
+        $result = $config->updateAccountMapping($line, $account_codes);
+        if ($result) {
+            $updated_count++;
         }
     }
     
-    setEventMessages($langs->trans("ConfigurationUpdated"), null, 'mesgs');
+    // Debug output
+    if (empty($debug_info)) {
+        setEventMessages("Debug: No form data received", null, 'warnings');
+    } else {
+        setEventMessages("Debug: " . implode(' | ', $debug_info), null, 'warnings');
+    }
+    
+    if ($updated_count > 0) {
+        setEventMessages($langs->trans("ConfigurationUpdated"), null, 'mesgs');
+    } else {
+        setEventMessages($langs->trans("NoChangesDetected"), null, 'warnings');
+    }
 }
 
 // Get current mappings
@@ -189,4 +205,5 @@ print '</div>';
 
 // Print footer
 llxFooter();
+?>
 ?>
\ No newline at end of file
diff --git a/core/class/declarationtva_config.class.php b/core/class/declarationtva_config.class.php
index 6049963..e381cca 100644
--- a/core/class/declarationtva_config.class.php
+++ b/core/class/declarationtva_config.class.php
@@ -112,12 +112,27 @@ class DeclarationTVA_Config
         if (!empty($account_codes)) {
             foreach ($account_codes as $account_code) {
                 if (!empty($account_code)) {
-                    $sql = "INSERT INTO " . MAIN_DB_PREFIX . "declarationtva_account_mappings 
-                            (entity, ca3_line, account_code, account_label, vat_rate, is_active, created_date) 
-                            VALUES (" . $this->entity . ", '" . $this->db->escape($ca3_line) . "', 
-                            '" . $this->db->escape($account_code) . "', '', 0, 1, NOW()) 
-                            ON DUPLICATE KEY UPDATE 
-                            is_active = 1, account_code = '" . $this->db->escape($account_code) . "'";
+                    // Check if mapping already exists
+                    $check_sql = "SELECT id FROM " . MAIN_DB_PREFIX . "declarationtva_account_mappings 
+                                 WHERE entity = " . $this->entity . " 
+                                 AND ca3_line = '" . $this->db->escape($ca3_line) . "' 
+                                 AND account_code = '" . $this->db->escape($account_code) . "'";
+                    $check_result = $this->db->query($check_sql);
+                    
+                    if ($check_result && $this->db->num_rows($check_result) > 0) {
+                        // Update existing mapping
+                        $sql = "UPDATE " . MAIN_DB_PREFIX . "declarationtva_account_mappings 
+                                SET is_active = 1 
+                                WHERE entity = " . $this->entity . " 
+                                AND ca3_line = '" . $this->db->escape($ca3_line) . "' 
+                                AND account_code = '" . $this->db->escape($account_code) . "'";
+                    } else {
+                        // Insert new mapping
+                        $sql = "INSERT INTO " . MAIN_DB_PREFIX . "declarationtva_account_mappings 
+                                (entity, ca3_line, account_code, account_label, vat_rate, is_active, created_date) 
+                                VALUES (" . $this->entity . ", '" . $this->db->escape($ca3_line) . "', 
+                                '" . $this->db->escape($account_code) . "', '', 0, 1, NOW())";
+                    }
                     $this->db->query($sql);
                 }
             }
diff --git a/langs/en_US/declarationtva.lang b/langs/en_US/declarationtva.lang
index 828dc0e..40f967e 100644
--- a/langs/en_US/declarationtva.lang
+++ b/langs/en_US/declarationtva.lang
@@ -370,3 +370,4 @@ SelectedAccounts = Selected Accounts
 AccountCount = Account Count
 MultiSelectHelp = Hold Ctrl (or Cmd on Mac) to select multiple accounts
 ErrorCSRFToken = Security token error. Please try again.
+NoChangesDetected = No changes detected in the configuration.
diff --git a/langs/fr_FR/declarationtva.lang b/langs/fr_FR/declarationtva.lang
index 356edbf..3318a9b 100644
--- a/langs/fr_FR/declarationtva.lang
+++ b/langs/fr_FR/declarationtva.lang
@@ -359,3 +359,4 @@ SelectedAccounts = Comptes sélectionnés
 AccountCount = Nombre de comptes
 MultiSelectHelp = Maintenez Ctrl (ou Cmd sur Mac) pour sélectionner plusieurs comptes
 ErrorCSRFToken = Erreur de jeton de sécurité. Veuillez réessayer.
+NoChangesDetected = Aucun changement détecté dans la configuration.