spectra extraction bug correction

src/main/java/fr/soleil/mambo/datasources/db/attributes/BufferedFormatsAttributeManager.java

@@ -82,12 +82,18 @@ public class BufferedFormatsAttributeManager extends BasicAttributeManager {
             tdbTimeBuffer.put(completeName, time);
             formatMap = tdbDataFormatBuffer;
         }
+        int dataFormat;
         Integer knownFormat = formatMap.get(completeName);
         if (knownFormat == null) {
-            knownFormat = Integer.valueOf(super.getFormat(completeName, historic));
+            dataFormat = super.getFormat(completeName, historic);
+            if (dataFormat > -1) {
+                knownFormat = Integer.valueOf(dataFormat);
                 formatMap.put(completeName, knownFormat);
             }
-        return knownFormat.intValue();
+        } else {
+            dataFormat = knownFormat.intValue();
+        }
+        return dataFormat;
     }
 
     // ///////////// //