Sorry didn't spot that. Could you clarify a few things for me.
As the code stands the input button should begin in an disabled state since it has an attribute disabled="disabled". Is that the case? Does it appearance suggest it is disabled, that is the style associated with the class is not making it look enabled when it is in fact disabled?
Presumably you then click the check_box_selector checkbox which turns it's state to disabled=false. If you then click the check_box_selector checkbox again you would expect the state to go to disabled=true but the problem is that is not happening. Is that right?
Would it be possible to post the html code that the browser gets rather than the php that generates the html?