Thank you.
I have the same issue with my update page.
<option value="<?php echo $row_WADAresidence['agent']; ?>" <?php if (!(strcmp($row_WADAresidence['agent'], ((isset($_POST["agent"]))?$_POST["agent"]:"")))) {echo "selected=\"selected\"";} ?>><?php echo $row_WADAresidence['agent']; ?></option>
<option value="None">Clear</option>
<?php
do {
?>
<option value="<?php echo $row_agents['Agent']?>"<?php if (!(strcmp($row_agents['Agent'], ((isset($_POST["agent"]))?$_POST["agent"]:"")))) {echo "selected=\"selected\"";} ?>><?php echo $row_agents['Agent']?></option>
Following from your suggestion on the insert page I can see that I need something like this:
((isset($_GET["invalid"])?ValidatedField("residenceupdate","Agent"):"".$row_WADAresidence["Agent"].""))
but I cannot seem to get it two work.