Comparing Two Numbers Fails

In a script, I am testing two values--$cur_time and $updated_time, and 
if their difference is less than or equal to 86400, some processing is 
supposed to occur. Just before the test, I have a print statement which 
displays the values needed for the if test to succeed, followed by the 
if test, followed by what to do if the test succeeds, starting with 
another print statement, which is supposed to show me on-screen that the 
test succeeds and I'm now into the processing code.


*** Snip ***


   $x = ($cur_time - $updated_time); // Don't worry, those variables 
really do exist.

   print "$showcode, $cur_time, $updated_time, $x\n"; // Display the 
variables in question before the test. This always works.

// This shows me what file is being processed, the current time,

// the time it was last updated, and the difference between the two.

// If $x is less than or equal to 86400, the test passes and processing 
continues.

// But even when the values all align and are good, it fails.

   if (($cur_time - $updated_time) <= 86400) { // 24 hours
     print Chosen: "$showcode, $cur_time, $updated_time\n"; // Show me 
what file should be on the report.

      // This doesn't work, and the rest of the processing never 
happens, so the test must have failed. But why?
}


Everything looks correct. It's a stupidly simple if statement. What 
could possibly be wrong with it?


I paired it down to the bare essentials and preloaded a couple variables 
for test purposes:


<?php
$showcode = "TEST";
$cur_time = time ();
$updated_time = ($cur_time - 50000); // Make like the test should pass.
$x = ($cur_time - $updated_time); // DO the math, mostly for short print 
statement.
   print "$showcode, $cur_time, $updated_time, $x\n";

// Everything's preloaded and correct.

   if ($cur_time - $updated_time <= 86400) //which it is ...

     print "Yes! $showcode, $x\n";
?>


When I run this, it works. What could possibly be wrong with the same 
decision statements in the first sample? The second sample is just a 
single print statement, not a block enclosed by braces, but so what? I 
should get the print statement that comes right after the "if" statement 
is the computed value of ($cur_time - $updated_time) is less than 86400, 
and as the foreach loop goes around, the first print statement shows me 
that there are indeed some files in the directory that meet this 
criterion. What's going on here? This is keep-it-simple-stupid simple.