ho trovato la soluzione!! FUNZIONA a chi può servire...ecco lo script:
<?php
@$actions = $_GET['actions'];
@$action = $_GET['action'];
@$cat = $_GET['cat'];
@$categoria = addslashes(trim($_POST['categoria']));
@$sotto_categoria = addslashes(trim($_POST['sotto_categoria']));
@$foot_categoria = addslashes(trim($_POST['foot_categoria']));

?>
<table width="900" border="0" align="center" cellpadding="0" cellspacing="0">
<form name="categorie" method="post" action="default.php?page=prodotti/ins_categoria&actions=add_cat<?php if (isset($action) or isset($actions)) {echo "&action=add_foot";} ?>"><tr>
<td colspan="3" class="style_add_azienda">[img]img/ins_cat.png[/img]INSERIMENTO CATEGORIE E SOTTOCATEGORIE </td>
</tr>
<tr>
<td colspan="3"> </td>
</tr>
<tr>
<td width="300" height="40" class="style_font">Categoria:</td>
<td width="258" height="40"><div align="left" ><input name="categoria" type="text" value="<?php echo $categoria; ?>" class="style_form" size="38"></div> </td>
<td height="40" class="style_pagine"><div align="left">[img]img/add.png[/img] aggiungi sottocategoria</div></td>
</tr>
<tr>
<td width="300" height="40" class="style_font"><?php if ($actions=="add_cat") {echo"Sottocategoria:";} ?> </td>
<td width="258" height="40"><div align="left" ><?php if ($actions=="add_cat") {echo"<input name=\"sotto_categoria\" type=\"text\" value=\"$sotto_categoria\" class=\"style_form\" size=\"38\"> ";} ?> </div></td>
<td height="40" class="style_font"><?php if ($actions=="add_cat") {echo"<div align=\"left\"><a href=\"default.php?page=prodotti/ins_categoria&action=add_foot&actions=add_cat\" onclick=\"document.categorie.submit(); return false;\"><img src=\"img/add.png\" width=\"26\" height=\"24\" align=\"absmiddle\" border=\"0\" /></a> aggiungi sottocategoria</div>";}?></td>
</tr>
<tr>
<td height="40" class="style_font"><?php if ($action=="add_foot" AND $actions =="add_cat") {echo"Sottocategoria:";} ?> </td>
<td height="40" class="style_font"><div align="left" ><?php if ($action=="add_foot" AND $actions =="add_cat") {echo"<input name=\"foot_categoria\" value=\"$foot_categoria\" type=\"text\" class=\"style_form\" size=\"38\" > ";} ?> </div></td>
<td height="40" class="style_font"> </td>
</tr>
<tr>
<td height="50" colspan="3" class="style_font"><div align="center"><input name="Image" type="Image" src="img/invia.png" /> </div></td>
</tr>
</form>
</table>