diff --git a/java/src/org/broadinstitute/sting/gatk/iterators/MergingSamRecordIterator2.java b/java/src/org/broadinstitute/sting/gatk/iterators/MergingSamRecordIterator2.java
index 44145f562..693ba08c5 100644
--- a/java/src/org/broadinstitute/sting/gatk/iterators/MergingSamRecordIterator2.java
+++ b/java/src/org/broadinstitute/sting/gatk/iterators/MergingSamRecordIterator2.java
@@ -138,7 +138,10 @@ public class MergingSamRecordIterator2 implements CloseableIterator<SAMRecord>,
         if (oldProgramGroupId != null) {
             final String newProgramGroupId = this.samHeaderMerger.getProgramGroupId(iterator.getReader(), oldProgramGroupId);
             record.setAttribute(SAMTag.PG.toString(), newProgramGroupId);
-        } else {
+        }
+
+        // if we don't have a read group, set one correctly
+        if (record.getAttribute(SAMTag.RG.toString()) == null) {
             List<SAMReadGroupRecord> readGroups = iterator.getReader().getFileHeader().getReadGroups();
             if (readGroups.size() == 1) {
                 record.setAttribute(SAMTag.RG.toString(), readGroups.get(0).getReadGroupId());
diff --git a/java/src/org/broadinstitute/sting/playground/gatk/walkers/PoolCaller.java b/java/src/org/broadinstitute/sting/playground/gatk/walkers/PoolCaller.java
index 1815866f3..656648342 100644
--- a/java/src/org/broadinstitute/sting/playground/gatk/walkers/PoolCaller.java
+++ b/java/src/org/broadinstitute/sting/playground/gatk/walkers/PoolCaller.java
@@ -1,21 +1,22 @@
 
 package org.broadinstitute.sting.playground.gatk.walkers;
 
-import net.sf.samtools.*;
-import org.broadinstitute.sting.gatk.*;
-import org.broadinstitute.sting.gatk.refdata.ReferenceOrderedData;
-import org.broadinstitute.sting.gatk.refdata.ReferenceOrderedDatum;
-import org.broadinstitute.sting.gatk.refdata.rodDbSNP;
-import org.broadinstitute.sting.gatk.refdata.rodGFF;
+import net.sf.samtools.SAMFileHeader;
+import net.sf.samtools.SAMReadGroupRecord;
+import net.sf.samtools.SAMRecord;
+import org.broadinstitute.sting.gatk.GenomeAnalysisTK;
+import org.broadinstitute.sting.gatk.LocusContext;
 import org.broadinstitute.sting.gatk.refdata.RefMetaDataTracker;
 import org.broadinstitute.sting.gatk.walkers.LocusWalker;
-import org.broadinstitute.sting.gatk.LocusContext;
-import org.broadinstitute.sting.playground.gatk.walkers.AlleleFrequencyWalker;
 import org.broadinstitute.sting.playground.utils.AlleleFrequencyEstimate;
-import org.broadinstitute.sting.utils.*;
+import org.broadinstitute.sting.utils.GenomeLoc;
+import org.broadinstitute.sting.utils.ReadBackedPileup;
+import org.broadinstitute.sting.utils.Utils;
 import org.broadinstitute.sting.utils.cmdLine.Argument;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Random;
 
 public class PoolCaller extends LocusWalker<AlleleFrequencyEstimate, String> 
 {
@@ -56,6 +57,7 @@ public class PoolCaller extends LocusWalker<AlleleFrequencyEstimate, String>
             caller.metricsFileName = "/dev/null";
             caller.lodThreshold = 5.0;
             caller.fourBaseMode = false;
+            caller.printMetrics = false;
             caller.initialize();
             callers.add(caller);
         }