spacewalk importing issue

[sisalcentos]

Hi i have an issue importing some centos 4 system in my spacewalk console.

When i register a system i get this error message: rhnreg_ks: ERROR: refreshing remote package list for System Profile

however i found the system in the list of spacewalk (1.9 version)

But I'm receiving this error in my email:

Exception reported from myhostname.mydomain.xxx
Time: Wed Jun 19 13:56:09 2013
Exception type
Exception while handling function registration.update_packages
Request object information:
URI: /XMLRPC
Remote Host: servername.mydomain.xxx
Server Name: myhostname.mydomain.xxx:80

[...]


Exception Handler Information
Traceback (most recent call last):
File "/usr/lib/python2.6/site-packages/spacewalk/server/apacheRequest.py", line 122, in call_function
response = apply(func, params)
File "/usr/share/rhn/server/handlers/xmlrpc/registration.py", line 921, in update_packages
server.save_packages()
File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnServer/server_wrapper.py", line 75, in save_packages
ret = self.save_packages_byid(self.server["id"], schedule=schedule)
File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnServer/server_packages.py", line 228, in save_packages_byid
h.execute_bulk(package_data)
File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnSQL/sql_base.py", line 197, in execute_bulk
ret = ret + apply(self.executemany, (), subdict)
File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnSQL/sql_base.py", line 172, in executemany
return apply(self._execute_wrapper, (self._executemany, ) + p, kw)
File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnSQL/driver_postgresql.py", line 273, in _execute_wrapper
retval = apply(function, p, kw)
File "/usr/lib/python2.6/site-packages/spacewalk/server/rhnSQL/driver_postgresql.py", line 309, in _executemany
self._real_cursor.executemany(self.sql, all_kwargs)
InternalError: -20243 : (package_arch_not_found) - Package architecture could not be found
CONTEXT: SQL statement "SELECT rhn_exception.raise_exception('package_arch_not_found')"
PL/pgSQL function "lookup_package_arch" line 14 at PERFORM


[...]

any ideas?

thanks a lot