Help - PHP Link Error??

Am using Dw with PHP and MySQL to set up a login page. When I do a 'check links sitewide' action before posting to my web server it comes up as having this broken link <?php echo $loginFormAction;?>.

How do I fix it? Have I done something silly in the code?

<div id="mainContent">
<h2> </h2>
<h2>Please Log In</h2>
<form id="form1" name="form1" method="POST" action="<?php echo $loginFormAction;?> ">
<table width="0" border="0" cellpadding="10">
<tr>
<td nowrap="nowrap">Username:</td>
<td><label>
<input type="text" name="user_name" id="user_name" />
</label></td>
</tr>
<tr>
<td nowrap="nowrap">Password:</td>
<td><label>
<input type="password" name="user_password" id="user_password" />
</label></td>
</tr>
<tr>
<td> </td>
<td><label>
<input type="submit" name="Submit" id="submit" value="Log In" />
</label></td>
</tr>
</table>
</form>
<p> </p>