problems with unchecking checkboxes

problems with unchecking checkboxes

Hi,
I'm using jquery-UI-package (version is up to date). So i love it but now I have problems with checkboxes.
 

I want to uncheck it with javascript. This my Code:

  1. var checkBox = document.getElementById("checkBoxId");
    if (checkBox.checked)
           checkBox.checked = false;

 
The checked-flag is set to false, but the checkbox-button looks like it is still checked. If I click that button ones more, for the user happens nothing. In real, the flag changes from false to true, but because the button looks already like checked, nothing change there.
 
How I can fix that problem?
 
Thank you
 
 
PS: Sorry for my bad english