diff --git a/source/org/thdl/tib/scanner/ByteDictionarySource.java b/source/org/thdl/tib/scanner/ByteDictionarySource.java
index a95efe0..eb8e775 100644
--- a/source/org/thdl/tib/scanner/ByteDictionarySource.java
+++ b/source/org/thdl/tib/scanner/ByteDictionarySource.java
@@ -305,14 +305,22 @@ public class ByteDictionarySource extends DictionarySource
 	    String tag;
 	    
 	    if (defTags==null) tag = Integer.toString(source[0]+1);
-	    else tag = defTags[source[0]];
+	    else
+	    {
+	    	if (source[0]<0 || source[0]>=defTags.length) return null;
+	    	tag = defTags[source[0]];	    
+	    }
 	    
 	    for (i=1; i<source.length; i++)
 	    {
 	        tag += ", ";
 	        
     	    if (defTags==null) tag += Integer.toString(source[i]+1);
-	        else tag += defTags[source[i]];    
+	        else
+	        {
+	        	if (source[i]<0 || source[i]>=defTags.length) return null;
+	        	tag += defTags[source[i]];
+	        }
 	    }
 
 		return tag;
diff --git a/source/org/thdl/tib/scanner/OnLineScannerFilter.java b/source/org/thdl/tib/scanner/OnLineScannerFilter.java
index 7ea4e63..b93125c 100644
--- a/source/org/thdl/tib/scanner/OnLineScannerFilter.java
+++ b/source/org/thdl/tib/scanner/OnLineScannerFilter.java
@@ -410,6 +410,7 @@ public class OnLineScannerFilter extends HttpServlet
                         pw.println("  <tr>");
                         if (ds!=null && !ds.isEmpty()) tag = ds.getTag(0);
                         else tag = "&nbsp;";
+                        if (tag==null) tag = "&nbsp;";
                         
                         pw.println("    <td width=\"20%\" rowspan=\""+ defs.def.length +"\" valign=\"top\">"+ word.getBookmark(tibetan) +"</td>");
                         pw.println("    <td width=\"12%\">"+ tag +"</td>");
@@ -421,6 +422,7 @@ public class OnLineScannerFilter extends HttpServlet
                             pw.println("  <tr>");
                             if (ds!=null && !ds.isEmpty()) tag = ds.getTag(i);
                             else tag = "&nbsp;";
+                            if (tag==null) tag = "&nbsp;";
                             pw.println("    <td width=\"12%\">"+ tag +"</td>");
                             pw.println("    <td width=\"68%\">" + defs.def[i] + "</td>");
                             //else pw.println("    <td width=\"80%\" colspan=\"2\">" + defs.def[i] + "</td>");