--- a/Filtered_kernel/include/CGAL/Filtered_predicate.h
+++ b/Filtered_kernel/include/CGAL/Filtered_predicate.h
@@ -165,11 +165,13 @@ Filtered_predicate<EP,AP,C2E,C2A,Protection>::
       Protect_FPU_rounding<Protection> p;
       try
        {
+std::cout <<"trying..." << std::endl;
          Ares res = ap(c2a(args)...);
+std::cout <<" OK"<< std::endl;
          if (is_certain(res))
            return get_certain(res);
        }
-      catch (Uncertain_conversion_exception&) {}
+      catch (Uncertain_conversion_exception&) {std::cout << "  catched"<< std::endl;}
     }