ok, I've checked on the site error_logs,
this is the output:

SELECT COUNT(*)
FROM site_CatLinks, site_Links
WHERE site_CatLinks.LinkID = site_Links.ID AND (site_Links.isValidated = 'Yes' AND site_CatLinks.CategoryID = '51421')

from main::_build_category at nph-build.cgi line 576
GT::SQL::Driver::MYSQL::sth (9854): Query execution took: 0.000293s from main::_build_category at nph-build.cgi line 576
GT::SQL::Driver::MYSQL::sth (9854): Executing query: SELECT * FROM site_Category WHERE ( ID = 51421 ) from Links::Build::build_category at Links::Build::b$
GT::SQL::Driver::MYSQL::sth (9854): Query execution took: 0.000341s from Links::Build::build_category at Links::Build::build_category line 21
GT::SQL::Driver::MYSQL::sth (9854): Executing query: SELECT Category_Template FROM site_Category WHERE ID = 51421 from Links::Category::template_set at /h$
GT::SQL::Driver::MYSQL::sth (9854): Query execution took: 0.000287s from Links::Category::template_set at /home/mysite/public_html/cgi-bin/admin/Links/Cat$
GT::SQL::Driver::MYSQL::sth (9854): Executing query: SELECT FatherID,ID FROM site_Category WHERE ID = 51421 from Links::Category::_parents at /home/inmrom$
GT::SQL::Driver::MYSQL::sth (9854): Query execution took: 0.000264s from Links::Category::_parents at /home/mysite/public_html/cgi-bin/admin/Links/Categor$
GT::SQL::Driver::MYSQL::sth (9854): Executing query:
SELECT site_Links.*
FROM site_CatLinks, site_Links
WHERE site_CatLinks.LinkID = site_Links.ID AND (site_Links.isValidated = 'Yes' AND site_CatLinks.CategoryID = '51421')
ORDER BY Top_Order DESC, isNew DESC,isPopular DESC,Title LIMIT 0, 10
from Links::Build::build_category at Links::Build::build_category line 82
GT::SQL::Relation (9854): Failed to execute query: '
SELECT site_Links.*
FROM site_CatLinks, site_Links
WHERE site_CatLinks.LinkID = site_Links.ID AND (site_Links.isValidated = 'Yes' AND site_CatLinks.CategoryID = '51421')
ORDER BY Top_Order DESC, isNew DESC,isPopular DESC,Title LIMIT 0, 10
' Reason: Got error 28 from table handler at /home/mysite/public_html/cgi-bin/admin/GT/SQL/Driver/MYSQL.pm line 117.
Can't call method "fetchall_hashref" on an undefined value at Links::Build::build_category line 87.

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Thanks in Advance
Bye From Italy