diff --git a/ACU/Trace.pm b/ACU/Trace.pm
index ec4677b..bf2b998 100644
--- a/ACU/Trace.pm
+++ b/ACU/Trace.pm
@@ -107,6 +107,7 @@ sub getIds ($)
 
 package TraceHandler;
 
+use Carp;
 use constant NO_ID_VALUE => "__#";
 
 sub new ($$)
@@ -164,6 +165,9 @@ sub start_element
 	    
 	$self->{values} = "";
     }
+    elsif ($element->{Name} ne "group" && $element->{Name} ne "name" && $element->{Name} ne "statut" && $element->{Name} ne "status" && $element->{Name} ne "log") {
+	croak "Not a valid trace XML: unknown tag ".$element->{Name};
+    }
 }
 
 sub characters
@@ -192,7 +196,7 @@ sub end_element
     }
     elsif ($element->{Name} eq "eval")
     {
-	delete $self->{parsed}{ids}{ $self->{inEval} } if (!$self->{parsed}{ids}{ $self->{inEval} });
+	#delete $self->{parsed}{ids}{ $self->{inEval} } if (!$self->{parsed}{ids}{ $self->{inEval} });
 	$self->{inEval} = "";
     }
     elsif ($element->{Name} eq "comment")