Newbie Question: Next & Previous links

I want to break up lengthy content into pages with next and previous links.

My content is stored in $text.

When using the following code my next page links work but when I click on a previous link I get a file not found error:

if (!isset($page)) $page=0;

$textarray = split("[PAGEBREAK]",$text);

$text=$textarray[$page];

if ($page !=0) {
$prevpage=$page - 1;
echo("<a href=\"PHP_SELF?page=$prevpage\">".
"Previous Page</a>");
}

echo ("" . $text . " ");

if ($page < count($textarray) - 1) {
$nextpage = $page + 1;
echo("<a href=\"$PHP_SELF?page=$nextpage\">".
"Next Page</a>");
}

Can anyone help?

You are missing a $ sign

if ($page !=0) {
$prevpage=$page - 1;
/**************|/
echo("<a href=\"PHP_SELF?page=$prevpage\">".
/*********************/
"Previous Page</a>");
}

that line should be

echo("<a href=\"$PHP_SELF?page=$prevpage\">".

Hope that helps

Andreas