diff --git a/Simulator.cpp b/Simulator.cpp
index 5c8684c..4b1c5b9 100644
--- a/Simulator.cpp
+++ b/Simulator.cpp
@@ -1514,6 +1514,25 @@ Simulator::ExecCollisionCheck( int& nCdInd, int& nObjInd, int nMoveType)
    return true ;
 }
 
+//----------------------------------------------------------------------------
+static int
+FindCollisionMarkId( const IGeomDB* pGeomDB, int nCollId)
+{
+   int nCollParId = pGeomDB->GetParentId( nCollId) ;
+   string sCollParName = "COLLISION" ;
+   pGeomDB->GetName( nCollParId, sCollParName) ;
+   if ( sCollParName != "COLLISION")
+      return nCollParId ;
+   else {
+      int nCollGprId = pGeomDB->GetParentId( nCollParId) ;
+      int nCollSolId = pGeomDB->GetFirstNameInGroup( nCollGprId, "SOLID") ;
+      if ( nCollSolId != GDB_ID_NULL)
+         return nCollSolId ;
+      else
+         return nCollGprId ;
+   }
+}
+
 //----------------------------------------------------------------------------
 bool
 Simulator::SetCollisionMark( int nCdInd, int nObjInd)
@@ -1521,10 +1540,8 @@ Simulator::SetCollisionMark( int nCdInd, int nObjInd)
    if ( m_pGeomDB == nullptr)
       return false ;
    m_nCollMarkId.clear() ;
-   int nCdGeoId = m_pGeomDB->GetParentId(  m_pGeomDB->GetParentId( m_CdId[nCdInd])) ;
-   int nCoGeoId = m_pGeomDB->GetParentId(  m_pGeomDB->GetParentId( m_CollObj[nObjInd].nFrameId)) ;
-   m_nCollMarkId.push_back( nCdGeoId) ;
-   m_nCollMarkId.push_back( nCoGeoId) ;
+   m_nCollMarkId.push_back( FindCollisionMarkId( m_pGeomDB, m_CdId[nCdInd])) ;
+   m_nCollMarkId.push_back( FindCollisionMarkId( m_pGeomDB, m_CollObj[nObjInd].nFrameId)) ;
    for ( auto nId : m_nCollMarkId)
       m_pGeomDB->SetMark( nId) ;
    return true ;