why is iconv not working as expected?

Hi there, I'm puzzled by the iconv() call from php. When I test it with cyrillic text, in the utf-8 or windows-1251 charsets, or when I try with iranian text, the following php call <?php echo @iconv($charset, 'ASCII//TRANSLIT', $texte)) ?> brings me only question marks "???????". What I don't understand is that lynx parses those same texts very well, and it is (I think?) based on the same iconv() library... What can I do to either tune my system or do the right call to iconv()? The aim is to have a nice search engine for SPIP, a GPL'd CMS, so the most portable answer will be the best ;) (I'm not on the php-general list, so please Cc: me.) -- Fil