diff --git a/numass-storage/src/main/java/inr/numass/storage/NumassDataLoader.java b/numass-storage/src/main/java/inr/numass/storage/NumassDataLoader.java
index 57390e6d..c017d43e 100644
--- a/numass-storage/src/main/java/inr/numass/storage/NumassDataLoader.java
+++ b/numass-storage/src/main/java/inr/numass/storage/NumassDataLoader.java
@@ -37,6 +37,7 @@ import java.time.Instant;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -169,7 +170,7 @@ public class NumassDataLoader extends AbstractLoader implements BinaryLoader<Env
                 throw new RuntimeException(ex);
             }
         }
-        
+
 //        LocalDateTime startTime = envelope.meta().get
         RawNMPoint raw = new RawNMPoint(envelope.meta().getDouble("external_meta.HV1_value", 0),
                 events,
@@ -240,7 +241,7 @@ public class NumassDataLoader extends AbstractLoader implements BinaryLoader<Env
     @Override
     public List<NMPoint> getNMPoints() {
         List<NMPoint> res = new ArrayList<>();
-        this.getPoints().stream().forEach((point) -> {
+        this.getPoints().stream().forEachOrdered((point) -> {
             res.add(readPoint(point));
         });
 //        res.sort((NMPoint o1, NMPoint o2) -> o1.getAbsouteTime().compareTo(o2.getAbsouteTime()));
@@ -256,6 +257,10 @@ public class NumassDataLoader extends AbstractLoader implements BinaryLoader<Env
                 }
             }
         });
+
+        res.sort((Envelope t, Envelope t1) -> t.meta().getInt("external_meta.point_index", -1)
+                .compareTo(t1.meta().getInt("external_meta.point_index", -1)));
+
         return res;
     }
 
diff --git a/numass-viewer/src/main/java/inr/numass/viewer/MspViewController.java b/numass-viewer/src/main/java/inr/numass/viewer/MspViewController.java
index 8d20c482..9db96c95 100644
--- a/numass-viewer/src/main/java/inr/numass/viewer/MspViewController.java
+++ b/numass-viewer/src/main/java/inr/numass/viewer/MspViewController.java
@@ -213,7 +213,7 @@ public class MspViewController implements Initializable {
         p.putValue("timestamp", last.getValue("timestamp").timeValue().plusMillis(10));
         for (String name : last.namesAsArray()) {
             if (!name.equals("timestamp")) {
-                p.putValue(name, Value.getNull());
+                p.putValue(name, Value.NULL);
             }
         }
         return p;
diff --git a/numass-viewer/src/main/java/inr/numass/viewer/NumassLoaderViewComponent.java b/numass-viewer/src/main/java/inr/numass/viewer/NumassLoaderViewComponent.java
index 05215f3a..03297b10 100644
--- a/numass-viewer/src/main/java/inr/numass/viewer/NumassLoaderViewComponent.java
+++ b/numass-viewer/src/main/java/inr/numass/viewer/NumassLoaderViewComponent.java
@@ -147,14 +147,14 @@ public class NumassLoaderViewComponent extends AnchorPane implements Initializab
         detectorDataExportButton.setOnAction(this::onExportButtonClick);
         lowChannelField.textProperty().bindBidirectional(channelSlider.lowValueProperty(), new NumberStringConverter());
         upChannelField.textProperty().bindBidirectional(channelSlider.highValueProperty(), new NumberStringConverter());
-        
+
         channelSlider.setLowValue(300);
         channelSlider.setHighValue(1900);
-        
+
         ChangeListener<? super Number> rangeChangeListener = (ObservableValue<? extends Number> observable, Number oldValue, Number newValue) -> {
             updateSpectrumPane();
         };
-        
+
         channelSlider.lowValueProperty().addListener(rangeChangeListener);
         channelSlider.highValueProperty().addListener(rangeChangeListener);
     }
@@ -209,11 +209,18 @@ public class NumassLoaderViewComponent extends AnchorPane implements Initializab
 
     private void updateSpectrumPane() {
         if (spectrumPlotFrame == null) {
-            spectrumPlotFrame = new JFreeChartFrame("spectrum", null, spectrumPlotPane);
+            Meta plotMeta = new MetaBuilder("plot")
+                    .setValue("xAxis.axisTitle", "U")
+                    .setValue("xAxis.axisUnits", "V")
+                    .setValue("yAxis.axisTitle", "count rate")
+                    .setValue("yAxis.axisUnits", "Hz")
+                    .setValue("legend.show", false);
+
+            spectrumPlotFrame = new JFreeChartFrame("spectrum", plotMeta, spectrumPlotPane);
         }
 
         if (spectrumData == null) {
-            spectrumData = new ChangeablePlottableData("", null);
+            spectrumData = new ChangeablePlottableData("spectrum", null);
             spectrumPlotFrame.add(spectrumData);
         }