Z-Index not working

Developers
1

I got the following sourcecode to adjust the setting of the chatwidget. The setting of the position works but the Z-Index is unchanged on the page - any idea what I am doing wrong or is this a bug in tawkt.to?

                        var Tawk_API=Tawk_API||{};
                        Tawk_API.visitor = {
                            name : '<?=cName?>',
                            email : '<?=cEmail?>',
                            hash : '<?=hash_hmac('sha256', cEmail, 'apikey')?>'
                        };
                        Tawk_API.customStyle = {
                            zIndex : 902,
                            visibility : {
                                desktop : {
                                    position : 'br',
                                    xOffset : 13,
                                    yOffset : 13
                                },
                                mobile : {
                                    position : 'br',
                                    xOffset : 80,
                                    yOffset : 62
                                }
                            }
                        };
                        var Tawk_LoadStart=new Date();
2

it’s working for me with
zIndex: ‘1200 !important’