Keywords la posturi luate din titlu

[florescualin]

Automat as vrea si fara pluginuri pentru ca am anumite pluginuri care se bat cap in cap cu cele spuse de voi. Eu am avut functia urmatoare:

function trim_text($str, $len, $el = '...')
{
  if (strlen($str) > $len) {
     $xl = strlen($el);
     if ($len < $xl) {
        return substr($str, 0, $len);
     }
     $str = substr($str, 0, $len-$xl);
     $spc = strrpos($str, ' ');
     if ($spc > 0) {
        $str = substr($str, 0, $spc);
     }
     return $str . $el;
  }
  return $str;
}  

function etichetele ($sString){
    return strtolower(trim(preg_replace("/([^a-zA-Z_-])+/", "-", $sString),""));
} 

<meta name="keywords" content="retete, reteta, <?php $keyword=etichetele($post->post_title);
$keyword = explode("-",$keyword);
$nrk = count(explode("-",$keyword));
$i = 0;
$array = explode(",", $keyword);
$output = implode(",", $array);
foreach ($keyword as $eticheta) { if ($eticheta != "" && strlen($eticheta)>=3) {
echo"".$eticheta.", "; }}?>" />
<?php } ?>

In header.php am aceasta functie insa de la o vreme imi da urmatoarea eroare:

<meta name="keywords" content="retete, reteta, <br />
<b>Warning</b>:  explode() expects parameter 2 to be string, array given in <b>/home2/user/public_html/numesite.ro/wp-content/themes/temamea/header.php</b> on line <b>29</b><br />
<br />
<b>Warning</b>:  explode() expects parameter 2 to be string, array given in <b>/home2/user/public_html/numesite.ro/wp-content/themes/temamea/header.php</b> on line <b>31</b><br />
<br />
<b>Warning</b>:  implode() [<a href='function.implode'>function.implode</a>]: Invalid arguments passed in <b>/home2/user/public_html/numesite.ro/wp-content/themes/temamea/header.php</b> on line <b>32</b><br />
cartofi, prajiti, " />

Keywordurile le pune ok insa afiseaza aceasta eroare si nu stiu de la ce ar putea fi.