diff --git a/Simulator.cpp b/Simulator.cpp
index e7372bb..8d1c24b 100644
--- a/Simulator.cpp
+++ b/Simulator.cpp
@@ -1290,8 +1290,11 @@ Simulator::ExecLineVmill( int nVmId, int nCurrTool, double dVmTdOffs, double dVm
 {
   // Recupero Zmap
    IVolZmap* pVZM = GetVolZmap( m_pGeomDB->GetGeoObj( nVmId)) ;
-   if ( pVZM == nullptr)
+   if ( pVZM == nullptr) {
+      string sOut = " --> GetVolZmap (" + ToString( nVmId) +") Error <--" ;
+      LOG_DBG_INFO( GetEMkLogger(), sOut.c_str())
       return false ;
+   }
   // Porto gli estremi nel riferimento opportuno dello Zmap
    Point3d ptHiL = ptHi ;  ptHiL.ToLoc( frVzmI) ;
    Vector3d vtHiL = vtHi ; vtHiL.ToLoc( frVzmI) ;
@@ -1322,7 +1325,17 @@ Simulator::ExecLineVmill( int nVmId, int nCurrTool, double dVmTdOffs, double dVm
       }
    }
   // Eseguo
-   return pVZM->MillingStep( nCurrTool, ptHiL, vtHiL, vtAiL, ptHfL, vtHfL, vtAfL) ;
+   bool bOk = pVZM->MillingStep( nCurrTool, ptHiL, vtHiL, vtAiL, ptHfL, vtHfL, vtAfL) ;
+   if ( ! bOk) {
+      if ( ExeGetDebugLevel() < 10) {
+         string sOut = "Zmap=" + ToString( nVmId) + " Tool=" + ToString( nCurrTool) +
+                       " Pi=(" + ToString( ptHiL) + ") Vi=(" + ToString( vtHiL) + ") Ai=(" + ToString( vtAiL) +
+                       ") Pf=(" + ToString( ptHfL) + ") Vf=(" + ToString( vtHfL) + ") Af=(" + ToString( vtAfL) + ")" ;
+         LOG_DBG_INFO( GetEMkLogger(), sOut.c_str())
+      }
+      LOG_DBG_INFO( GetEMkLogger(), " --> MillingStep Error <--")
+   }
+   return bOk ;
 }
 
 //----------------------------------------------------------------------------