fix the bugs of mergeTwoKmer when nextK mod 4 == 0
diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerUtil.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerUtil.java
index c4d6401..697f537 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerUtil.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerUtil.java
@@ -175,7 +175,7 @@
 						- j] & 0xff) >> (8 - posNeedToMove)) | (kmerNext[offsetNext + lengthNext
 						- j - 1] << posNeedToMove));
 			}
-			if ( (nextK % 4) * 2 + posNeedToMove > 8) {
+			if ( nextK % 4 == 0 || (nextK % 4) * 2 + posNeedToMove > 8) {
 				mergedKmer[0] = (byte) (kmerNext[offsetNext] >> (8 - posNeedToMove));
 			}
 		}
diff --git a/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/example/kmer/KmerUtilTest.java b/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/example/kmer/KmerUtilTest.java
index 4b6e180..854bb47 100644
--- a/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/example/kmer/KmerUtilTest.java
+++ b/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/example/kmer/KmerUtilTest.java
@@ -105,6 +105,11 @@
 		String text7 = "GCTGAC";
 		merged = KmerUtil.mergeTwoKmer(7, kmer5, 0, kmer5.length, 6, kmer7, 0, kmer7.length);
 		Assert.assertEquals(text5+text7, Kmer.recoverKmerFrom(7+6, merged, 0, merged.length));
+		
+		byte[] kmer8 = Kmer.compressKmer(4, array, 1);
+		String text8 = "GCTG";
+		merged = KmerUtil.mergeTwoKmer(7, kmer5, 0, kmer5.length, 4, kmer8, 0, kmer8.length);
+		Assert.assertEquals(text5+text8, Kmer.recoverKmerFrom(7+4, merged, 0, merged.length));
 
 	}
 	@Test