diff --git a/src/clj/job_streamer/control_bus/component/apps.clj b/src/clj/job_streamer/control_bus/component/apps.clj
index 6c66689..8765269 100644
--- a/src/clj/job_streamer/control_bus/component/apps.clj
+++ b/src/clj/job_streamer/control_bus/component/apps.clj
@@ -51,11 +51,18 @@
                                     classpaths))
             proc (.exec (Runtime/getRuntime) cmd)]
         (log/debug (clojure.string/join " " cmd))
+        (letfn [(print-err []
+                      (with-open [rdr (io/reader (.getErrorStream proc))]
+                        (->> (line-seq rdr)
+                             (map #(log/error %))
+                             doall)))]
+          (.start (Thread. print-err)))
         (with-open [rdr (io/reader (.getInputStream proc))]
           (->> (line-seq rdr)
                (map #(clojure.string/split % #":" 2))
                (map (fn [[category class-name]]
-                      {(keyword "batch-component" category) class-name}))
+                      (let [c {(keyword "batch-component" category) class-name}]
+                        (log/debugf "%s was scaned." (pr-str c)) c)))
                (reduce #(merge-with conj %1 %2)
                        {:batch-component/batchlet []
                         :batch-component/item-reader []
diff --git a/src/java/net/unit8/job_streamer/control_bus/BatchComponentScanner.java b/src/java/net/unit8/job_streamer/control_bus/BatchComponentScanner.java
index efe5e17..28f15e1 100644
--- a/src/java/net/unit8/job_streamer/control_bus/BatchComponentScanner.java
+++ b/src/java/net/unit8/job_streamer/control_bus/BatchComponentScanner.java
@@ -67,8 +67,8 @@ Set<String>  jarEntryNames(File zipFile) throws IOException {
     }
 
     String decideRefName(Class<?> clazz) {
-        System.err.println(clazz);
-        System.err.println(clazz.getAnnotations());
+        System.err.println("decideRefName: clazz: " + clazz);
+        System.err.println("decideRefName: annotation: " + clazz.getAnnotations());
         Annotation[] annotations = clazz.getDeclaredAnnotations();
         for (Annotation annotation : annotations) {
             if (annotation instanceof Named && !Strings.isNullOrEmpty(((Named) annotation).value())) {
@@ -83,29 +83,41 @@ void pickOverBatchComponent(String resourcePath, ClassLoader cl) {
             String className = resourcePath
                     .substring(0, resourcePath.lastIndexOf(".class"))
                     .replace('/', '.').replace('\\', '.');
+            System.err.println("className: " + className);
             if (className.startsWith("java.")
                     || className.startsWith("javax.")
                     || className.startsWith("com.sun.")
                     || className.startsWith("sun.")
                     || className.startsWith("clojure.")) {
+                System.err.println("This is ignored with wrong package name");
                 return;
             }
             try {
                 Class<?> clazz = cl.loadClass(className);
                 if (Batchlet.class.isAssignableFrom(clazz)) {
-                    container.batchlets.add(decideRefName(clazz));
+                  System.err.println("  This clazz is Batchlet");
+                  container.batchlets.add(decideRefName(clazz));
                 } else if (ItemReader.class.isAssignableFrom(clazz)) {
-                    container.itemReaders.add(decideRefName(clazz));
+                  System.err.println("  This clazz is ItemReader");
+                  container.itemReaders.add(decideRefName(clazz));
                 } else if (ItemWriter.class.isAssignableFrom(clazz)) {
-                    container.itemWriters.add(decideRefName(clazz));
+                  System.err.println("  This clazz is ItemWriter");
+                  container.itemWriters.add(decideRefName(clazz));
                 } else if (ItemProcessor.class.isAssignableFrom(clazz)) {
-                    container.itemProcessors.add(decideRefName(clazz));
+                  System.err.println("  This clazz is ItemProcessor");
+                  container.itemProcessors.add(decideRefName(clazz));
                 } else if (isListener(clazz)) {
-                    container.listeners.add(decideRefName(clazz));
+                  System.err.println("  This clazz is Listener");
+                  container.listeners.add(decideRefName(clazz));
                 } else if (Throwable.class.isAssignableFrom(clazz)) {
-                    container.throwables.add(decideRefName(clazz));
+                  System.err.println("  This clazz is Throwable");
+                  container.throwables.add(decideRefName(clazz));
+                } else {
+                  System.err.println("  This clazz is ignored");
                 }
             } catch (ClassNotFoundException | NoClassDefFoundError e) {
+                System.err.println("  This clazz is ignored with Exception");
+                e.printStackTrace();
                 // ignore
             }
         }