diff --git a/src/graph-path-validation.cc b/src/graph-path-validation.cc
index ffd704c53d146c37fd6124b3f4d4839b48c10dd1..baa5183669e117118558d0d8d688c4b5463ecdd7 100644
--- a/src/graph-path-validation.cc
+++ b/src/graph-path-validation.cc
@@ -91,6 +91,7 @@ namespace hpp {
 
       PathPtr_t pathNoCollision;
       ConstraintSetPtr_t c = HPP_DYNAMIC_PTR_CAST(ConstraintSet, path->constraints());
+      hppDout(info, (c?"Using edge path validation":"Using default path validation"));
       PathValidationPtr_t validation (c
           ? c->edge()->pathValidation()
           : pathValidation_);
diff --git a/src/graph-steering-method.cc b/src/graph-steering-method.cc
index 381d301a69b2866fcb128ae008dd4d994d546023..1094f82e3019600113304481eeae1e9f0afce788 100644
--- a/src/graph-steering-method.cc
+++ b/src/graph-steering-method.cc
@@ -74,6 +74,9 @@ namespace hpp {
         return PathPtr_t ();
       }
       PathPtr_t path;
+      if (possibleEdges.empty()) {
+        hppDout (info, "No edge found.");
+      }
       while (!possibleEdges.empty()) {
         if (possibleEdges.back ()->build (path, q1, q2)) {
           return path;
diff --git a/src/graph/edge.cc b/src/graph/edge.cc
index 43c142e05100b306cbc311829d1e80bdc1be8f54..9e9ee772d3ba91b32658c3b34f3423b49563653d 100644
--- a/src/graph/edge.cc
+++ b/src/graph/edge.cc
@@ -278,11 +278,15 @@ namespace hpp {
       {
         ConstraintSetPtr_t constraints = pathConstraint ();
         constraints->configProjector ()->rightHandSideFromConfig(q1);
-        if (!constraints->isSatisfied (q1) || !constraints->isSatisfied (q2)) {
-          return false;
+        if (constraints->isSatisfied (q1)) {
+          if (constraints->isSatisfied (q2)) {
+            path = (*steeringMethod_->get()) (q1, q2);
+            return true;
+          }
+          hppDout(info, "q2 does not satisfy the constraints");
         }
-	path = (*steeringMethod_->get()) (q1, q2);
-        return true;
+        hppDout(info, "q1 does not satisfy the constraints");
+        return false;
       }
 
       bool Edge::applyConstraints (core::NodePtr_t nnear, ConfigurationOut_t q) const
@@ -346,19 +350,35 @@ namespace hpp {
         if (!useCache) configs_.col (0) = q2;
 
         assert (waypoints_[0].first);
-        if (!waypoints_[0].first->applyConstraints (q1, configs_.col (0)))
+        if (!waypoints_[0].first->applyConstraints (q1, configs_.col (0))) {
+          hppDout (info, "Waypoint edge " << name() << ": applyConstraints failed at waypoint 0."
+              << "\nUse cache: " << useCache
+              );
           return false;
-        if (!waypoints_[0].first->build (p, q1, configs_.col (0)))
+        }
+        if (!waypoints_[0].first->build (p, q1, configs_.col (0))) {
+          hppDout (info, "Waypoint edge " << name() << ": build failed at waypoint 0."
+              << "\nUse cache: " << useCache
+              );
           return false;
+        }
         pv->appendPath (p);
 
         for (std::size_t i = 1; i < waypoints_.size (); ++i) {
           assert (waypoints_[i].first);
           if (!useCache) configs_.col (i) = q2;
-          if (!waypoints_[i].first->applyConstraints (configs_.col(i-1), configs_.col (i)))
+          if (!waypoints_[i].first->applyConstraints (configs_.col(i-1), configs_.col (i))) {
+            hppDout (info, "Waypoint edge " << name() << ": applyConstraints failed at waypoint " << i << "."
+                << "\nUse cache: " << useCache
+                );
             return false;
-          if (!waypoints_[i].first->build (p, configs_.col(i-1), configs_.col (i)))
+          }
+          if (!waypoints_[i].first->build (p, configs_.col(i-1), configs_.col (i))) {
+            hppDout (info, "Waypoint edge " << name() << ": build failed at waypoint " << i << "."
+                << "\nUse cache: " << useCache
+                );
             return false;
+          }
           pv->appendPath (p);
         }
 
diff --git a/src/problem-solver.cc b/src/problem-solver.cc
index 8c3b4347f475f2b66ae80ce3e50699df186141a7..e3dca5478d1e232b9270eb3dc59fac04bf08d270 100644
--- a/src/problem-solver.cc
+++ b/src/problem-solver.cc
@@ -27,8 +27,6 @@
 #include <hpp/constraints/convex-shape-contact.hh>
 
 #include <hpp/core/random-shortcut.hh>
-#include <hpp/core/discretized-collision-checking.hh>
-#include <hpp/core/continuous-collision-checking/progressive.hh>
 #include <hpp/core/path-optimization/partial-shortcut.hh>
 #include <hpp/core/roadmap.hh>
 #include <hpp/core/steering-method-straight.hh>
@@ -49,7 +47,7 @@
 #include "hpp/manipulation/graph-steering-method.hh"
 #include "hpp/manipulation/path-optimization/config-optimization.hh"
 
-#ifdef HPP_MANIPULATION_HAS_WHOLEBODY_STEP
+#if HPP_MANIPULATION_HAS_WHOLEBODY_STEP
 #include <hpp/wholebody-step/small-steps.hh>
 #include "hpp/manipulation/path-optimization/small-steps.hh"
 #endif
diff --git a/src/problem.cc b/src/problem.cc
index 155bb89a32a86abec45dfc0be8649cb77c1a46d2..fba71b74d3e6c8325374705d091935d7d9cc5e12 100644
--- a/src/problem.cc
+++ b/src/problem.cc
@@ -15,6 +15,9 @@
 // hpp-manipulation. If not, see <http://www.gnu.org/licenses/>.
 
 #include <hpp/manipulation/problem.hh>
+
+#include <hpp/core/discretized-collision-checking.hh>
+
 #include <hpp/manipulation/weighed-distance.hh>
 #include <hpp/manipulation/graph-steering-method.hh>
 
@@ -25,6 +28,7 @@ namespace hpp {
     {
       Parent::steeringMethod (GraphSteeringMethod::create (this));
       distance (WeighedDistance::create (robot, graph_));
+      setPathValidationFactory(core::DiscretizedCollisionChecking::create, 0.05);
     }
 
     void Problem::constraintGraph (const graph::GraphPtr_t& graph)