diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
index ded9f36..59159e9 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
@@ -14,9 +14,11 @@
  */
 package edu.uci.ics.genomix.type;
 
-import java.io.IOException;
 import java.io.DataInput;
 import java.io.DataOutput;
+import java.io.IOException;
+import java.io.Serializable;
+
 import org.apache.hadoop.io.BinaryComparable;
 import org.apache.hadoop.io.WritableComparable;
 import org.apache.hadoop.io.WritableComparator;
@@ -26,8 +28,12 @@
  * It was used to generate the graph in which phase the kmer length doesn't change.
  * Thus the size of bytes doesn't change either.
  */
-public class KmerBytesWritable extends BinaryComparable implements WritableComparable<BinaryComparable> {
-    protected int size;
+public class KmerBytesWritable extends BinaryComparable implements Serializable, WritableComparable<BinaryComparable> {
+    /**
+	 * 
+	 */
+	private static final long serialVersionUID = 1L;
+	protected int size;
     protected byte[] bytes;
     protected int kmerlength;
 
diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java
index 6c02468..3319cad 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/VKmerBytesWritable.java
@@ -3,12 +3,16 @@
 import org.apache.hadoop.io.WritableComparator;
 
 public class VKmerBytesWritable extends KmerBytesWritable {
+    /**
+     * 
+     */
+    private static final long serialVersionUID = 1L;
     public static final int DEFAULT_KMER_LENGTH = 21;
-    
-    public VKmerBytesWritable(){
+
+    public VKmerBytesWritable() {
         this(DEFAULT_KMER_LENGTH);
     }
-    
+
     public VKmerBytesWritable(int k) {
         super(k);
     }
diff --git a/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/KMerSequenceWriterFactory.java b/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/KMerSequenceWriterFactory.java
index 46e162c..413c73b 100644
--- a/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/KMerSequenceWriterFactory.java
+++ b/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/KMerSequenceWriterFactory.java
@@ -58,8 +58,6 @@
 				reEnterCount.set(bitmap, count);
 				reEnterKey.set(kmer, keyStart, keyLength);
 				writer.append(reEnterKey, reEnterCount);
-				// @mark: this method can not used for read in hadoop 0.20.2.
-				// writer.appendRaw(kmer, keyStart, keyLength, reEnterCount);
 			} catch (IOException e) {
 				throw new HyracksDataException(e);
 			}
diff --git a/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/ReadsKeyValueParserFactory.java b/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/ReadsKeyValueParserFactory.java
index d4b88ba..79ad195 100644
--- a/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/ReadsKeyValueParserFactory.java
+++ b/genomix/genomix-hyracks/src/main/java/edu/uci/ics/genomix/dataflow/ReadsKeyValueParserFactory.java
@@ -74,7 +74,7 @@
 
                 if (bReversed) {
                     /** first kmer */
-                    kmer.setByRead(array, 0);
+                    kmer.setByReadReverse(array, 0);
                     next = 0;
                     pre = GeneCode.getAdjBit(array[k]);
                     InsertToFrame(kmer, pre, next, writer);
diff --git a/genomix/genomix-hyracks/src/test/java/edu/uci/ics/genomix/example/jobrun/JobRunTest.java b/genomix/genomix-hyracks/src/test/java/edu/uci/ics/genomix/example/jobrun/JobRunTest.java
index 3eb4347..bef13b5 100644
--- a/genomix/genomix-hyracks/src/test/java/edu/uci/ics/genomix/example/jobrun/JobRunTest.java
+++ b/genomix/genomix-hyracks/src/test/java/edu/uci/ics/genomix/example/jobrun/JobRunTest.java
@@ -15,7 +15,6 @@
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
-import org.apache.hadoop.io.BytesWritable;
 import org.apache.hadoop.io.SequenceFile;
 import org.apache.hadoop.mapred.FileInputFormat;
 import org.apache.hadoop.mapred.FileOutputFormat;
@@ -196,10 +195,10 @@
                 }
                 SequenceFile.Reader reader = new SequenceFile.Reader(dfs, path, conf);
                 
-                KmerBytesWritable key = (KmerBytesWritable) ReflectionUtils.newInstance(reader.getKeyClass(), conf);
+//                KmerBytesWritable key = (KmerBytesWritable) ReflectionUtils.newInstance(reader.getKeyClass(), conf);
+                KmerBytesWritable key = new KmerBytesWritable(conf.getInt(GenomixJob.KMER_LENGTH, GenomixJob.DEFAULT_KMER));
                 KmerCountValue value = (KmerCountValue) ReflectionUtils.newInstance(reader.getValueClass(), conf);
 
-                int k = conf.getInt(GenomixJob.KMER_LENGTH, 25);
                 while (reader.next(key, value)) {
                     if (key == null || value == null) {
                         break;