diff --git a/piwigotools/__init__.py b/piwigotools/__init__.py
index c74e6e7..adf18f6 100644
--- a/piwigotools/__init__.py
+++ b/piwigotools/__init__.py
@@ -60,8 +60,9 @@ class Piwigo(piwigo.Piwigo):
 
     @property
     def plan(self):
-        return { i["name"] : i["id"] for i in self.pwg.categories.getList(recursive=True, fullname=True)['categories'] }
-
+        plan = { i["name"] : i["id"] for i in self.pwg.categories.getList(recursive=True, fullname=True)['categories'] }
+        plan[""] = 0
+        return plan
 
     def _checkarg(fn):
         def checking(self, *args, **kw):
diff --git a/piwigotools/interface.py b/piwigotools/interface.py
index dd377f2..86afc4e 100644
--- a/piwigotools/interface.py
+++ b/piwigotools/interface.py
@@ -70,11 +70,12 @@ class Run:
                                     ' ', 
                                     progressbar.Timer()],
                             maxval=self._qin.qsize()).start()
-        for thread in self._threads:
-            thread.start()
-        while not self._qout.full():
-            time.sleep(0.1) # sleep 0.1s
-            pbar.update(self._qout.qsize())
+        if self._qin.qsize():
+            for thread in self._threads:
+                thread.start()
+            while not self._qout.full():
+                time.sleep(0.1) # sleep 0.1s
+                pbar.update(self._qout.qsize())
         pbar.finish()    
         return self._qerr
 
diff --git a/piwigotools/main.py b/piwigotools/main.py
index 44d4eba..bfae269 100644
--- a/piwigotools/main.py
+++ b/piwigotools/main.py
@@ -35,7 +35,7 @@ VERBS = {
                 "description" : "upload file in piwigo gallery",
                 "arg" : 
                     {
-                        "category" : {"type":"string", "default":"/", "help":"destination category of piwigo gallery"},
+                        "category" : {"type":"string", "default":"", "help":"destination category of piwigo gallery"},
                         "source" : {"type":"string", "default":"*.jpg", "help":"path of upload picture"},
                         "url" :  {"type":"string", "default":"", "help":"url of piwigo gallery"},
                         "user" :  {"type":"string", "default":"", "help":"user of piwigo gallery"},
@@ -49,7 +49,7 @@ VERBS = {
                 "description" : "download image from piwigo gallery",
                 "arg" : 
                     {
-                        "category" : {"type":"string", "default":"/", "help":"source category of piwigo gallery"},
+                        "category" : {"type":"string", "default":"", "help":"source category of piwigo gallery"},
                         "dest" : {"type":"string", "default":".", "help":"path of destination"},
                         "url" :  {"type":"string", "default":"", "help":"url of piwigo gallery"},
                         "user" :  {"type":"string", "default":"", "help":"user of piwigo gallery"},
@@ -63,7 +63,7 @@ VERBS = {
                 "description" : "synchronization between path and piwigo gallery",
                 "arg" : 
                     {
-                        "category" : {"type":"string", "default":"/", "help":"category of piwigo gallery"},
+                        "category" : {"type":"string", "default":"", "help":"category of piwigo gallery"},
                         "source" : {"type":"string", "default":".", "help":"path of picture"},
                         "url" :  {"type":"string", "default":"", "help":"url of piwigo gallery"},
                         "user" :  {"type":"string", "default":"", "help":"user of piwigo gallery"},
@@ -199,6 +199,28 @@ def main():
             piwigo.logout()
             if run.error:
                 parser.error(run.strerror)
+        if verb == "sync":
+            ana = Analyse('Analyze')
+            ana.start()
+            try:
+                piwigo = Piwigo(url=options.url)
+                piwigo.login(options.user, options.password)
+                # check
+                options.source = os.path.abspath(options.source)
+                if not os.path.isdir(options.source):
+                    raise Exception("%s is not directory" % options.source)
+                piwigo.iscategory(options.category)
+                # treatment
+                run = Run(verb, options.thread)
+                kw = purge_kw(options.__dict__,('user','password','url','source','category','thread'))
+                ana.stop()
+            except Exception as e:
+                ana.stop()
+                raise e
+            run.start()
+            piwigo.logout()
+            if run.error:
+                parser.error(run.strerror)
     except Exception as e:
         parser.error(e)
         sys.exit(1)