OK thanks. Here's the form code from the html template:
<form name="questionnaire" action="questionnaire.php" method="get">
<table border="0" cellspacing="0" cellpadding="0" class="default" name="maintable" width="98%" vspace="0" hspace="0">
<tr>
<td colspan="6">
<div align="center"><font color="#990000">{message}</font></div>
</td>
</tr>
<tr>
<td colspan="6"> </td>
</tr>
<tr>
<td colspan="6"><b>Please supply your name and the full name, address
and telephone number of your company:</b></td>
</tr>
<tr>
<td colspan="6">
<div align="right">{nmes} Your Name:
<input type="text" name="custname" value="{FName} {LName}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">{cmes} Company Name:
<input type="text" name="compname" value="{Company}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">{ames} Company Address:
<input type="text" name="add1" value="{add1}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">
<input type="text" name="add2" value="{add2}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">
<input type="text" name="add3" value="{add3}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">{pmes} Postcode:
<input type="text" name="postcode" value="{postcode}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">{tmes} Telephone Number:
<input type="text" name="telno" value="{telcode} {telnumber}">
</div>
</td>
</tr>
<tr>
<td colspan="6">
<div align="right">
<input type="submit" name="send1" value="Next">
</div>
</td>
</tr>
</table>
</form>
and here's an example of the PHP code:
if ($send1)
{
if ((!$custname) || (!$compname) || (!$add1) || (!postcode) || (!$telno))
{
$message = "Please enter the details where requested.";
$Tpl = new Template;
$Tpl -> set_file("Main", "questionnaire.ihtml"

;
$Tpl -> set_var(array("FName" => $FName,
"LName" => $LName,
"Company" => $Company,
"telcode" => $telcode,
"telnumber" => $telnumber,
"message" => $message,
"add1" => $add1,
"add2" => $add2,
"add3" => $add3,
"postcode" => $postcode));
// all set send it out..
$Tpl -> parse("out", "Main"

;
$Tpl -> p("out"

;
}
}
When the method is "get" this code works fine, when the user submits the form "send1" is set and if fields such as custname and compname are not filled in the "if" statement is run. However when the method is "post" in the same situation send1 is not set and the "if" statement is ignored.
Hope this makes sense.
Cath.