Easy Checkbox Update

[eluser]Fielder[/eluser]
I think I'm missing something really simple..

My form successfully works for adding a new user, and when updating a user status FROM 0(inactive) to 1(active). However, it does not work FROM 1 to 0 when editing. It just doesn't change the value to NULL or blank.

View:

Code:

<input type="checkbox" name="user_status" value="1" <?php if ($user_status == '1') { echo " CHECKED"; } ?> />

Database Setup:

Code:

user_status is a tinyint, min length 1, Null Yes, default NULL