How to change the state of check box from another method/Thread?

Here's i created a check box:

@FXML
private CheckBox cB_0_0 = new CheckBox("cB_0_0");

And then i'm trying to check this check box from method in Controller class

    public void setCheckBoxOn(Point p) {
        // getting CheckBox object cB_0_0
        cB_0_0.setSelected(true);
    }

But in fact the checkbox is not activated in gui...

What am I doing wrong?

UPD: btw I'm calling method setCheckBoxOn from another Thread, can it be the main problem?