diff --git a/src/osg/AnimationPath.cpp b/src/osg/AnimationPath.cpp
index 382e6e222..1c333fe3a 100644
--- a/src/osg/AnimationPath.cpp
+++ b/src/osg/AnimationPath.cpp
@@ -46,4 +46,37 @@ bool AnimationPath::getMatrix(double time,Matrix& matrix)
 
 bool AnimationPath::getInverse(double time,Matrix& matrix)
 {
+    if (_timeKeyMap.empty()) return false;
+
+    TimeKeyMap::iterator second = _timeKeyMap.lower_bound(time);
+    if (second==_timeKeyMap.begin())
+    {
+        second->second.getInverse(matrix);
+    }
+    else if (second!=_timeKeyMap.end())
+    {
+        TimeKeyMap::iterator first = second;
+        --first;        
+        
+        // we have both a lower bound and the next item.
+
+        // deta_time = second.time - first.time
+        double delta_time = second->first - first->first;
+
+        if (delta_time==0.0)
+            first->second.getInverse(matrix);
+        else
+        {
+            Key key;
+            key.interpolate((time - first->first)/delta_time,
+                            first->second,
+                            second->second);
+            key.getInverse(matrix);
+        }        
+    }
+    else // (second==_timeKeyMap.end())
+    {
+        _timeKeyMap.rbegin().base()->second.getInverse(matrix);
+    }
+    return true;
 }
diff --git a/src/osgUtil/Optimizer.cpp b/src/osgUtil/Optimizer.cpp
index 5422fd113..bf0144c1f 100644
--- a/src/osgUtil/Optimizer.cpp
+++ b/src/osgUtil/Optimizer.cpp
@@ -41,7 +41,9 @@ void Optimizer::optimize(osg::Node* node, unsigned int options)
     
     if (options & SHARE_DUPLICATE_STATE)
     {
-    #if !defined(WIN32) || defined(_STLPORT_VERSION)
+    #if (defined(_MSC_VER) && _MSC_VER<13 && !defined(_STLPORT_VERSION))
+        osg::notify(osg::INFO)<<"Warning: VisualStudio 6.0 build, unable to run state optimizer"<<std::endl; 
+    #else
         StateVisitor osv;
         node->accept(osv);
         osv.optimize();