diff --git a/ruby/lib/jam_ruby/models/rsvp_request.rb b/ruby/lib/jam_ruby/models/rsvp_request.rb
index 689aad72e..f30851efe 100644
--- a/ruby/lib/jam_ruby/models/rsvp_request.rb
+++ b/ruby/lib/jam_ruby/models/rsvp_request.rb
@@ -182,7 +182,7 @@ module JamRuby
             end
 
             if rsvp_slot.chosen && r[:accept]
-              raise StateError, "The #{rsvp_slot.instrument_id} slot has already been approved for another user."
+              raise StateError, "All RSVP slots for the #{rsvp_slot.instrument_id} have been already approved."
             end
 
             if r[:accept]
diff --git a/web/app/assets/javascripts/accounts_session_detail.js b/web/app/assets/javascripts/accounts_session_detail.js
index c43a8b537..a93d0b1c7 100644
--- a/web/app/assets/javascripts/accounts_session_detail.js
+++ b/web/app/assets/javascripts/accounts_session_detail.js
@@ -101,7 +101,18 @@
 
       rest.updateRsvpRequest(rsvpId, params)
         .done(refreshSessionDetail)
-        .fail(app.ajaxError);
+        .fail(function(jqXHR, textStatus, errorMessage) {
+          if (jqXHR.status === 400) {
+            app.notify(
+              {
+                title: "Unable to Approve RSVP",
+                text: jqXHR.responseJSON.message
+              });
+          }
+          else {
+            app.ajaxError(jqXHR, textStatus, errorMessage);
+          }
+        });
     }
 
     function declineRsvpRequest(e) {
@@ -132,6 +143,9 @@
       });
 
       context.JK.bindHoverEvents();
+      // context.JK.bindInstrumentHover($('#pendingRSVPs'));
+      // context.JK.bindInstrumentHover($('#session-rsvps'));
+      // context.JK.bindInstrumentHover($('#still-needed'));
     }
 
     function loadSessionData() {
@@ -243,7 +257,7 @@
             $.each(pending_rsvp_request.instrument_list, function (index, instrument) {
               var instrumentId = instrument == null ? null : instrument.id;
               var inst = context.JK.getInstrumentIcon24(instrumentId);
-              instrumentLogoHtml += '<img data-instrument-id="' + instrumentId + '" src="' + inst + '" width="24" height="24" />&nbsp;';
+              instrumentLogoHtml += '<img title="' + instrumentId + '" hoveraction="instrument" data-instrument-id="' + instrumentId + '" src="' + inst + '" width="24" height="24" />&nbsp;';
             })
           }
 
@@ -281,7 +295,7 @@
           $.each(approved_rsvp.instrument_list, function(index, instrument) {
             var instrumentId = instrument == null ? null : instrument.id;
             var inst = context.JK.getInstrumentIcon24(instrumentId);
-            instrumentLogoHtml += '<img src="' + inst + '" width="24" height="24" />&nbsp;';
+            instrumentLogoHtml += '<img title="' + instrumentId + '" hoveraction="instrument" data-instrument-id="' + instrumentId + '" src="' + inst + '" width="24" height="24" />&nbsp;';
           });
         }
 
@@ -312,7 +326,7 @@
 
         rsvpHtml = context._.template(
           $("#template-account-session-rsvp").html(),
-          {id: approved_rsvp.id, user_id: approved_rsvp.user_id, avatar_url: avatar_url,
+          {id: approved_rsvp.id, avatar_url: avatar_url,
             user_name: approved_rsvp.name, instruments: instrumentLogoHtml,
             latency: latencyHtml, is_owner: sessionData.isOwner, request_id: request_id},
           {variable: 'data'}
@@ -346,7 +360,7 @@
 
         resultHtml += context._.template(
           $("#template-account-invited").html(),
-          {avatar_url: avatar_url, user_id: invitation.reciever_id},
+          {avatar_url: avatar_url, user_id: invitation.receiver_id},
           {variable: 'data'}
         );
       });
diff --git a/web/app/assets/javascripts/findSession.js b/web/app/assets/javascripts/findSession.js
index df765fb3a..98db4761f 100644
--- a/web/app/assets/javascripts/findSession.js
+++ b/web/app/assets/javascripts/findSession.js
@@ -85,6 +85,9 @@
           context.JK.bindHoverEvents();
           $ssSpinner.hide();
         });
+
+      // context.JK.bindInstrumentHover($(CATEGORY.ACTIVE.id));
+      // context.JK.bindInstrumentHover($(CATEGORY.SCHEDULED.id));
     }
 
     /***************** ACTIVE SESSIONS *****************/
diff --git a/web/app/assets/javascripts/jamkazam.js b/web/app/assets/javascripts/jamkazam.js
index 08d79d34a..d8fb6e4aa 100644
--- a/web/app/assets/javascripts/jamkazam.js
+++ b/web/app/assets/javascripts/jamkazam.js
@@ -123,11 +123,11 @@
      */
     function ajaxError(jqXHR, textStatus, errorMessage) {
 
-      if (jqXHR.status == 404) {
+      if (jqXHR.status === 404) {
         logger.error("Unexpected ajax error: " + textStatus + ", msg:" + errorMessage);
         app.notify({title: "Oops!", text: "What you were looking for is gone now."});
       }
-      else if (jqXHR.status = 422) {
+      else if (jqXHR.status === 422) {
         logger.error("Unexpected ajax error: " + textStatus + ", msg: " + errorMessage + ", response: " + jqXHR.responseText);
         // present a nicer message
         try {
diff --git a/web/app/assets/javascripts/sessionList.js b/web/app/assets/javascripts/sessionList.js
index 06d26efa6..d58218dbf 100644
--- a/web/app/assets/javascripts/sessionList.js
+++ b/web/app/assets/javascripts/sessionList.js
@@ -369,7 +369,7 @@
         var track = participant.tracks[j];
         logger.debug("Find:Finding instruments. Participant tracks:", participant.tracks);
         var inst = context.JK.getInstrumentIcon24(track.instrument_id);
-        instrumentLogoHtml += '<img src="' + inst + '" width="24" height="24" />&nbsp;';
+        instrumentLogoHtml += '<img title="' + track.instrument_id + '" hoveraction="instrument" data-instrument-id="' + track.instrument_id + '" src="' + inst + '" width="24" height="24" />&nbsp;';
       }
 
       var id = participant.user.id;
@@ -400,7 +400,7 @@
         for (j=0; j < user.instrument_list.length; j++) {
           var instrument = user.instrument_list[j];
           var inst = context.JK.getInstrumentIcon24(instrument.id);
-          instrumentLogoHtml += '<img src="' + inst + '" width="24" height="24" />&nbsp;';
+          instrumentLogoHtml += '<img title="' + instrument.id + '" hoveraction="instrument" data-instrument-id="' + instrument.id + '" src="' + inst + '" width="24" height="24" />&nbsp;';
         }
       }
 
diff --git a/web/app/assets/javascripts/utils.js b/web/app/assets/javascripts/utils.js
index b83d901c7..2afdd2f53 100644
--- a/web/app/assets/javascripts/utils.js
+++ b/web/app/assets/javascripts/utils.js
@@ -239,6 +239,9 @@
       var instrumentId = $element.attr('data-instrument-id');
 
       if(instrumentId) {
+        if (instrumentId === "null") {
+          instrumentId = "not specified";
+        }
         context.JK.hoverBubble($element, instrumentId, options);
       }
       else {