How do I get a PHP to run from HTML?

I have an HTML menu where the menu items are an unnumbered list. Here is one of the list items:

<li><a href="verifycart.php?ukey=12345">Verify Cart</a></li>

When I select this option from the menu the verifycart.php code executes. BUT, the variable is NOT passed. Question 1 - How do I pass data/variable to the PHP from here?
Here is the .php code:

<?php
    error_reporting(E_ALL);
    include ("config.inc.php");
    $ukey = htmlspecialchars(trim($_POST['ukey']));
    $ukey="12345";
                        
    $conn = mysql_connect("localhost", "X", "Y.") or die('Verify DB Failure ' . mysql_error());
    mysql_select_db("test");
                  
    $result = mysql_query("SELECT * FROM itemhdr WHERE itemhdr.ukey = '$ukey'");
               
           if (!$result) {
               die('QUERY ERROR: verifyupload ' . mysql_error());
           }
                        
          $row = mysql_fetch_assoc($result);
          $vcount = $row['verifycount'];
                  
echo "INSIDE PHP " .$ukey;
echo "|";                                             
echo "VCOUNT " .$vcount;                        
                              
    mysql_close($conn);
                        
?>

Question 2 - Why doesn't $ukey get set via the POST?

Thanks in advance for your help.