diff --git a/html/admin/setup.php b/html/admin/setup.php
index 747de087a..f9c75d581 100644
--- a/html/admin/setup.php
+++ b/html/admin/setup.php
@@ -332,7 +332,7 @@ $account=$cn->count_sql("select * from pg_database where datname=lower('".domain
 if ($account == 0 ) {
 
   echo "Creation of ".domaine."account_repository";
-  if ( DEBUG=='false') ob_start();
+  if ( ! DEBUG) ob_start();
   $cn->exec_sql("create database ".domaine."account_repository encoding='utf8'");
   $cn=new Database();
   $cn->start();
@@ -341,10 +341,10 @@ if ($account == 0 ) {
   $cn->execute_script("sql/account_repository/constraint.sql");
   $cn->commit($cn);
 
- if ( DEBUG=='false') ob_end_clean();
+ if ( ! DEBUG) ob_end_clean();
 
   echo "Creation of Modele1";
-  if ( DEBUG=='false') ob_start();
+  if ( ! DEBUG) ob_start();
   $cn->exec_sql("create database ".domaine."mod1 encoding='utf8'");
 
   $cn=new Database(1,'mod');
@@ -354,19 +354,19 @@ if ($account == 0 ) {
   $cn->execute_script('sql/mod1/constraint.sql');
   $cn->commit();
 
-  if ( DEBUG=='false') ob_end_clean();
+  if ( ! DEBUG) ob_end_clean();
 
   echo "Creation of Modele2";
   $cn->exec_sql("create database ".domaine."mod2 encoding='utf8'");
   $cn=new Database(2,'mod');
   $cn->start();
-  if ( DEBUG=='false') { ob_start();  }
+  if ( ! DEBUG) { ob_start();  }
   $cn->execute_script('sql/mod1/schema.sql');
   $cn->execute_script('sql/mod2/data.sql');
   $cn->execute_script('sql/mod1/constraint.sql');
   $cn->commit();
 
- if ( DEBUG=='false') ob_end_clean();
+ if ( ! DEBUG) ob_end_clean();
 
  }// end if
 // Add a french accountancy model
@@ -423,7 +423,7 @@ echo '<hr>';
  	}
    }
 
- if (DEBUG=='false') ob_end_clean();
+ if (! DEBUG) ob_end_clean();
  echo "<h2 class=\"info\">Voil&agrave; tout est install&eacute; ;-) </H2>";
 ?>
 <A HREF="../index.php">Connectez-vous à PhpCompta</A>
diff --git a/html/ajax_ledger.php b/html/ajax_ledger.php
index 6e4fd3459..7a62b85ac 100644
--- a/html/ajax_ledger.php
+++ b/html/ajax_ledger.php
@@ -372,7 +372,8 @@ case 'save':
     }
     catch (Exception $e)
     {
-        echo $e->getMessage();
+      if ( DEBUG )   echo $e->getMessage();
+      alert( "Changement impossible: on ne peut pas changer la date dans une période fermée");
     }
     $html=ob_get_contents();
     ob_clean();
diff --git a/include/class_database.php b/include/class_database.php
index 418677af8..02921d1e0 100644
--- a/include/class_database.php
+++ b/include/class_database.php
@@ -118,11 +118,11 @@ class Database
             $this->array=$p_array;
             if ( $p_array==null )
             {
-                $this->ret=pg_query($this->db,$p_string);
+                $this->ret=@pg_query($this->db,$p_string);
             }
             else
             {
-                $this->ret=pg_query_params($this->db,$p_string,$p_array);
+                $this->ret=@pg_query_params($this->db,$p_string,$p_array);
             }
             if ( ! $this->ret )
             {
@@ -215,7 +215,7 @@ class Database
     function execute_script($script)
     {
 
-        if ( DEBUG=='false' ) ob_start();
+        if ( ! DEBUG ) ob_start();
         $hf=fopen($script,'r');
         if ( $hf == false )
         {
@@ -279,7 +279,7 @@ class Database
             if ( $this->exec_sql($sql) == false )
             {
                 $this->rollback();
-                if ( DEBUG=='false' ) ob_end_clean();
+                if ( ! DEBUG ) ob_end_clean();
                 print "ERROR : $sql";
                 exit();
             }
@@ -288,7 +288,7 @@ class Database
             print "<hr>";
         } // while (feof)
         fclose($hf);
-        if ( DEBUG=='false' ) ob_end_clean();
+        if ( ! DEBUG ) ob_end_clean();
     }
     /*!
      * \brief Get version of a database, the content of the
@@ -346,7 +346,7 @@ class Database
                 " from the version ".$this->get_version()." to $to</h3> </li>";
 
                 $this->execute_script($add.'sql/patch/upgrade'.$i.'.sql');
-                if ( DEBUG=='false' ) ob_start();
+                if ( ! DEBUG ) ob_start();
                 // specific for version 4
                 if ( $i == 4 )
                 {
@@ -425,7 +425,7 @@ class Database
                     $country=$this->get_value ("select pr_value from parameter where pr_id='MY_COUNTRY'");
                     $this->execute_script($add."sql/patch/upgrade61.".$country.".sql");
                 }
-                if ( DEBUG == 'false') ob_end_clean();
+                if ( ! DEBUG ) ob_end_clean();
             }
         }
         echo '</ul>';
diff --git a/include/constant.php b/include/constant.php
index 8caf65b47..dfb8db1b8 100644
--- a/include/constant.php
+++ b/include/constant.php
@@ -48,7 +48,7 @@ define ('MAX_ARTICLE',9);
 define ('MAX_CAT',15);
 define ('MAX_FORECAST_ITEM',10);
 
-define ("DEBUG","false");
+define ("DEBUG",false);
 
 // Erreur
 define ("NOERROR",0);