I've found a solution in the joomsef.php line 1170 :
// always remove Itemid and store it in a separate column
if (!is_null($uri->getVar('Itemid'))) {
$Itemid = $uri->getVar('Itemid');
$uri->delVar('Itemid');
}
I just comment these lines :
// always remove Itemid and store it in a separate column
/*if (!is_null($uri->getVar('Itemid'))) {
$Itemid = $uri->getVar('Itemid');
$uri->delVar('Itemid');
}*/
Because, when you create a link to K2 category (mainmenu) you need the ItemId but in Joomsef.php it's always remove so I just comment to keep the itemid !!!
Bye
++