Have problem with code for the news..undefined offset?

Hi guys! This is the code:

[syntaxhighlighter brush=php,first-line=1,highlight=0,collapse=false,html-script=false]$news_tags=$data['news_tags'];
if ($news_tags=="" { echo "There are no tags."; } else {
$exploded_tags = explode(", ", $news_tags);
$i="1"; for ($z = 0; $i <= 5; $i++) {
if ($exploded_tags[$i] == "" {
break; }
echo "<a href='".BASEDIR."search.php?method=OR&fields=0&stext=".$exploded_tags[$i]."&stype=news&submit.x=24&submit.y=20' alt='' title='$exploded_tags[$i]'><span>$exploded_tags[$i]</span></a>, ";
}
}[/syntaxhighlighter]

In Errors section in my admin panel, It keeps telling me that there is Undefined offset: 4 on line 5. The code is working perfectly, but how i can remove this error?