I'm trying to set up a cookie that, for each visit to a page, counts to 12, and then starts over at one again.

Code:
 // if there is no cookie, set one or if it's greater than 12, set it back to one since there's only 12 images
 if(!isset($_COOKIE['c_idximg']) || ($_COOKIE['c_idximg'] > 12)) { 
     setcookie("c_idximg",1, time()+86400*7); }
 else {
      // next page visit, it already exist, so advance it by one
	    $imgNUM = $_COOKIE['c_idximg'];
        $imgNUM = $imgNUM + 1; // advance by one
        setcookie("c_idximg",$imgNUM, time()+86400*7); 
  }

// output the values to see what they are!!
   echo $imgNUM.' this is imgNUM<br>';
   echo $_COOKIE["c_idximg"].' this is the cookie'; // this is ONE MORE than "imgNUM". WTH??
What's freaking me out here, when I output the two values as above:
1. "$imgNUM" is always one value higher than the cookie value.
2. The cookie will count to 13 before resetting to one.

Uhhh, I'm probably an idiot, but what's going on there that I don't get?

edit: obviously I have no idea how to spell "Advnace" ...