Both .css and .js files must be registered to all other skins.

bt5/erp5_slideshow_style/SkinTemplateItem/portal_skins/erp5_slideshow_core.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="Folder" module="OFS.Folder"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>_objects</string> </key>
+            <value>
+              <tuple/>
+            </value>
+        </item>
+        <item>
+            <key> <string>id</string> </key>
+            <value> <string>erp5_slideshow_core</string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string></string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

bt5/erp5_slideshow_style/SkinTemplateItem/portal_skins/erp5_slideshow_style/slides.css.xml → bt5/erp5_slideshow_style/SkinTemplateItem/portal_skins/erp5_slideshow_core/slides.css.xml

@@ -6,6 +6,10 @@
     </pickle>
     <pickle>
       <dictionary>
+        <item>
+            <key> <string>_Cacheable__manager_id</string> </key>
+            <value> <string>http_cache</string> </value>
+        </item>
         <item>
             <key> <string>_EtagSupport__etag</string> </key>
             <value> <string>ts15240428.47</string> </value>

bt5/erp5_slideshow_style/SkinTemplateItem/portal_skins/erp5_slideshow_style/slides.js.xml → bt5/erp5_slideshow_style/SkinTemplateItem/portal_skins/erp5_slideshow_core/slides.js.xml

@@ -6,6 +6,10 @@
     </pickle>
     <pickle>
       <dictionary>
+        <item>
+            <key> <string>_Cacheable__manager_id</string> </key>
+            <value> <string>http_cache</string> </value>
+        </item>
         <item>
             <key> <string>_EtagSupport__etag</string> </key>
             <value> <string>ts11000946.61</string> </value>

bt5/erp5_slideshow_style/bt/revision

-1
+2
\ No newline at end of file

bt5/erp5_slideshow_style/bt/template_skin_id_list

+erp5_slideshow_core
 erp5_slideshow_style
\ No newline at end of file