GET variable coming up empty when inserting integers

$distance=$_GET['distance'];
if($distance='' || !is_numeric($distance)){$distance=10000;}

Code (markup):

When I echo $distance, if I entered a number in the field, $distance comes back empty....
if I entered a non-numeric string or if I don't enter anything, $distance comes back as 10000

Why would that be?

Im using a form.....

<form method="get" action="index.php">
<input type="text" name="distance"/>
<input type="submit" name="submit" value="Search"/>
</form>

Code (markup):

When I enter 295 into the form field, the URL looks like: http://www.......com/index.html?distance=295&submit=Search

 

if($distance==''

PHP:

You forgot an equal sign.

 

Thanks, I see that now...... I appreciate the help