--- a/Plugin/ViewerPrefetchPolicy.cpp	Fri Nov 27 21:45:21 2015 +0100
+++ b/Plugin/ViewerPrefetchPolicy.cpp	Fri Nov 27 22:05:51 2015 +0100
@@ -74,9 +74,9 @@
     }
 
     std::string compression = path.substr(0, separator + 1);
-    std::string instanceId = path.substr(separator + 1);
+    std::string instanceAndFrame = path.substr(separator + 1);
 
-    instanceId = instanceId.substr(0, instanceId.find('_'));
+    std::string instanceId = instanceAndFrame.substr(0, instanceAndFrame.find('_'));
 
     Json::Value instance;
     if (!GetJsonFromOrthanc(instance, context_, "/instances/" + instanceId) ||
@@ -100,6 +100,7 @@
     }
 
     const Json::Value& instances = series["Slices"];
+
     if (instances.type() != Json::arrayValue)
     {
       return;
@@ -108,7 +109,7 @@
     Json::Value::ArrayIndex position = 0;
     while (position < instances.size())
     {
-      if (instances[position] == instanceId)
+      if (instances[position] == instanceAndFrame)
       {
         break;
       }