Probelms with 'make clean'

[vittorio]

Yesterday, after portsnap(-ping)  with fetch & update, first I upgraded the 
portupgrade port of my freebsd 6.1 fresh box by means of
make;make deinstall reinstall clean

Then  I started to upgrade my kde installation issuing
portupgrade 'kde*' but it invariably failed complaining: 

[an example with kdeaddons-konq-plugins-3.5.3]
NbBSD# portupgrade 'kdead*'
--->  Session started at: Sun, 11 Jun 2006 09:42:59 +0000
--->  Upgrade of misc/konq-plugins started at: Sun, 11 Jun 2006 09:44:47 +0000
--->  Upgrading 'kdeaddons-konq-plugins-3.5.2' 
to 'kdeaddons-konq-plugins-3.5.3' (misc/konq-plugins)
--->  Build of misc/konq-plugins started at: Sun, 11 Jun 2006 09:44:47 +0000
--->  Building '/usr/ports/misc/konq-plugins'
===>  Cleaning for qt-3.3.6_2
===>  Cleaning for gmake-3.80_2
===>  Cleaning for libtool-1.5.22_2
===>  Cleaning for kdebase-3.5.3_1
===>  Cleaning for kdelibs-3.5.3
make: don't know how to make clean. Stop
*** Error code 2 

So I had to recompile the ports with the usual
make;make deinstall reinstall;
which works smoothly but

make clean 
  
[here is an example with kdeaccessibility 3.5.3]

===>   Registering installation for kdeaccessibility-3.5.3
NbBSD# make clean
===>  Cleaning for qt-3.3.6_2
===>  Cleaning for gmake-3.80_2
===>  Cleaning for libtool-1.5.22_2
===>  Cleaning for kdelibs-3.5.3
make: don't know how to make clean. Stop
*** Error code 2


Where am I wrong? What did I mess up? AND... What should I do to fix it
Ciao
Vittorio

PS With packages different from kde portupgrade and 'make clean' seem to work 
properly.