Ho modificato ulteriormente il codice. Non ho piu' l'errore perche' il file php viene trovato. Comunque non riesco ad ottenere l'istruzione <DIV .... </DIV>:
<?php

if ($titpag== 'Home') {
$fl0_1=getcwd().'/inpaghome/Allcatsup_1.php';
$fl0_2=getcwd().'/inpaghome/ay_2.php';


$newsInHomeSx = array($fl0_1, );
$newsInHomeDx = array($fl0_2);
$quantenewsSx = count($newsInHomeSx);


echo "

<DIV STYLE='position:absolute; margin-left:12.5cm; margin-top:9.7cm; line-height: 5px;'>
<iframe src='./inpaghome/supcollet_2.php' width='450' scrolling='no' frameborder='0'>
</iframe>
</DIV>
<iframe src='./inpaghome/catmonol_1.php' width='450' scrolling='no' frameborder='0'>
</iframe>
";

for($i=0;$i<$quantenewsSx;$i++){

echo "

<DIV STYLE='position:absolute; margin-left:4.5cm;'>
<p><img src='images/filetto_separatore.jpg' width='650' height='1' alt='separatore'/></p>
</DIV>
";

if(isset($newsInHomeDx[$i])) {

echo "
<DIV STYLE='position:absolute; margin-left:12.5cm; line-height: 5px;'>
<iframe src=$newsInHomeDx[$i]; width='450' scrolling='no' frameborder='0'>
</iframe>
</DIV>
";
}

echo "
<iframe src=$newsInHomeSx[$i]; width='450' scrolling='no' frameborder='0'>
</iframe>
";

}
}

?>