diff --git a/main/src/com/google/refine/model/changes/DataExtensionChange.java b/main/src/com/google/refine/model/changes/DataExtensionChange.java
index 4a3463174..4deebf612 100644
--- a/main/src/com/google/refine/model/changes/DataExtensionChange.java
+++ b/main/src/com/google/refine/model/changes/DataExtensionChange.java
@@ -293,9 +293,7 @@ public class DataExtensionChange implements Change {
         writer.write("columnTypeCount="); writer.write(Integer.toString(_columnTypes.size())); writer.write('\n');
         for (ReconType type : _columnTypes) {
             try {
-                if(type == null) {
-                    writer.write("null");
-                } else { 
+                if(type != null) {
                     JSONWriter jsonWriter = new JSONWriter(writer);
                     type.write(jsonWriter, options);
 		}
@@ -409,7 +407,9 @@ public class DataExtensionChange implements Change {
                 columnTypes = new ArrayList<ReconType>(count);
                 for (int i = 0; i < count; i++) {
                     line = reader.readLine();
-		    if (line != null) {
+		    if (line == null || line.length() == 0) {
+			columnTypes.add(null);
+		    } else {
 			columnTypes.add(ReconType.load(ParsingUtilities.evaluateJsonStringToObject(line)));
 		    }
                 }
diff --git a/main/src/com/google/refine/model/recon/ReconciledDataExtensionJob.java b/main/src/com/google/refine/model/recon/ReconciledDataExtensionJob.java
index b0bffd8df..c1441bd5a 100644
--- a/main/src/com/google/refine/model/recon/ReconciledDataExtensionJob.java
+++ b/main/src/com/google/refine/model/recon/ReconciledDataExtensionJob.java
@@ -105,8 +105,10 @@ public class ReconciledDataExtensionJob {
             String s = ParsingUtilities.inputStreamToString(is);
             JSONObject o = ParsingUtilities.evaluateJsonStringToObject(s);
           
-	    // Extract the column metadata
-	    gatherColumnInfo(o.getJSONArray("meta"), columns);    
+	    if(columns.size() == 0) {
+		// Extract the column metadata
+		gatherColumnInfo(o.getJSONArray("meta"), columns);    
+	    }
 	  
             Map<String, ReconciledDataExtensionJob.DataExtension> map = new HashMap<String, ReconciledDataExtensionJob.DataExtension>();
             if (o.has("rows")){
diff --git a/main/webapp/modules/core/MOD-INF/controller.js b/main/webapp/modules/core/MOD-INF/controller.js
index 404e55070..08b76e2fc 100644
--- a/main/webapp/modules/core/MOD-INF/controller.js
+++ b/main/webapp/modules/core/MOD-INF/controller.js
@@ -478,7 +478,8 @@ function init() {
       "styles/dialogs/custom-tabular-exporter-dialog.less",
 
       "styles/reconciliation/recon-dialog.less",
-      "styles/reconciliation/standard-service-panel.less"
+      "styles/reconciliation/standard-service-panel.less",
+      "styles/reconciliation/extend-data-preview-dialog.less",
     ]
   );
 
diff --git a/main/webapp/modules/core/scripts/dialogs/extend-data-preview-dialog.js b/main/webapp/modules/core/scripts/dialogs/extend-data-preview-dialog.js
index b78e1a851..622cf194c 100644
--- a/main/webapp/modules/core/scripts/dialogs/extend-data-preview-dialog.js
+++ b/main/webapp/modules/core/scripts/dialogs/extend-data-preview-dialog.js
@@ -165,28 +165,18 @@ ExtendReconciledDataPreviewDialog.prototype._show = function(properties) {
   var suggestConfig = $.extend({}, this._serviceMetadata.suggest.property);
   suggestConfig.key = null;
   suggestConfig.query_param_name = "prefix";
-  /* var suggestConfig = {
-      filter: '(all type:/type/property)'
-  };
-  if ((this._column.reconConfig) && (this._column.reconConfig.type)) {
-    suggestConfig.filter = '(all type:/type/property (any namespace:/type/object namespace:' + this._column.reconConfig.type.id + '))';
-  } */
 
   this._elmts.addPropertyInput.suggestP(suggestConfig).bind("fb-select", function(evt, data) {
-    var expected = data.expected_type;
     self._addProperty({
       id : data.id,
       name: data.name,
-      /* expected: {
-        id: expected.id,
-        name: expected.name
-      } */
     });
   });
 };
 
 ExtendReconciledDataPreviewDialog.prototype._update = function() {
-  this._elmts.previewContainer.empty().text("Querying THE service...");
+  this._elmts.previewContainer.empty().html(
+	'<div bind="progressPanel" class="extend-data-preview-progress"><img src="images/large-spinner.gif" /></div>');
 
   var self = this;
   var params = {
@@ -291,7 +281,9 @@ ExtendReconciledDataPreviewDialog.prototype._renderPreview = function(data) {
       var cell = row[c];
       if (cell !== null) {
         if ($.isPlainObject(cell)) {
-          $('<a>').attr("href", "http://www.freebase.com/view" + cell.id).text(cell.name).appendTo(td);
+          $('<a>').attr("href",
+		this._serviceMetadata.identifierSpace + cell.id
+		).attr("target", "_blank").text(cell.name).appendTo(td);
         } else {
           $('<span>').text(cell).appendTo(td);
         }
@@ -315,21 +307,21 @@ ExtendReconciledDataPreviewDialog.prototype._removeProperty = function(id) {
 ExtendReconciledDataPreviewDialog.prototype._findProperty = function(id) {
   var properties = this._extension.properties;
   for(var i = properties.length - 1; i >= 0; i--) {
-    if (properties[i].id == path) {
+    if (properties[i].id == id) {
        return properties[i];
     }
   }
   return null;
 }
 
-ExtendReconciledDataPreviewDialog.prototype._constrainProperty = function(path) {
+ExtendReconciledDataPreviewDialog.prototype._constrainProperty = function(id) {
   var self = this;
-  var property = this._findProperty(path);
+  var property = this._findProperty(id);
 
   var frame = DialogSystem.createDialog();
   frame.width("500px");
 
-  var header = $('<div></div>').addClass("dialog-header").text("Constrain " + path.join(" > ")).appendTo(frame);
+  var header = $('<div></div>').addClass("dialog-header").text("Constrain " + id).appendTo(frame);
   var body = $('<div></div>').addClass("dialog-body").appendTo(frame);
   var footer = $('<div></div>').addClass("dialog-footer").appendTo(frame);
 
diff --git a/main/webapp/modules/core/styles/views/extend-data-preview-dialog.less b/main/webapp/modules/core/styles/reconciliation/extend-data-preview-dialog.less
similarity index 94%
rename from main/webapp/modules/core/styles/views/extend-data-preview-dialog.less
rename to main/webapp/modules/core/styles/reconciliation/extend-data-preview-dialog.less
index 006e87306..220a4610a 100644
--- a/main/webapp/modules/core/styles/views/extend-data-preview-dialog.less
+++ b/main/webapp/modules/core/styles/reconciliation/extend-data-preview-dialog.less
@@ -69,3 +69,12 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   vertical-align: top;
   margin-left: 5px;
   }
+
+.extend-data-preview-progress {
+  text-align: center;
+}
+
+.extend-data-preview-progress img {
+  padding: 45%;
+  display: inline-block;
+}