Hi, I met this problem in recent days. I fixed dbus-interface.c in lxseesion with attached patch and it works now.
I don't know the modification is good or not. However I hope this can help others with systemd install. Thanks.
diff -Nur lxsession-0.4.9.2/lxsession-logout/dbus-interface.c lxsession-0.4.9.2_mod/lxsession-logout/dbus-interface.c --- lxsession-0.4.9.2/lxsession-logout/dbus-interface.c 2013-04-13 05:02:19.000000000 +0800 +++ lxsession-0.4.9.2_mod/lxsession-logout/dbus-interface.c 2014-04-11 13:32:14.474933488 +0800 @@ -283,7 +283,7 @@ void dbus_logind_PowerOff (GError **error) { - logind_call_function ("PowerOff", TRUE, error); + logind_call_function ("PowerOff", TRUE, NULL); } gboolean @@ -295,7 +295,7 @@ void dbus_logind_Reboot (GError **error) { - logind_call_function ("Reboot", TRUE, error); + logind_call_function ("Reboot", TRUE, NULL); } gboolean @@ -307,7 +307,7 @@ void dbus_logind_Suspend (GError **error) { - logind_call_function ("Suspend", TRUE, error); + logind_call_function ("Suspend", TRUE, NULL); } gboolean @@ -319,7 +319,7 @@ void dbus_logind_Hibernate (GError **error) { - logind_call_function ("Hibernate", TRUE, error); + logind_call_function ("Hibernate", TRUE, NULL); } /*** ConsoleKit mechanism ***/