the form action is to post to a differant page:
<form action="blog_Update.php?id=<?php echo(rawurlencode($row_WADAblog['id'])); ?>" method="post" name="WADAUpdateForm" id="WADAUpdateForm">
it is set to post to blog_Update.php (PHP is case sensitive), the name of the page you sent is blog-update.php though:
<form action="blog-update.php?id=<?php echo(rawurlencode($row_WADAblog['id'])); ?>" method="post" name="WADAUpdateForm" id="WADAUpdateForm">