Sending information by getJSON

I have a redirect by getJSON, but a few days ago it stopped working for a screen, I can not find the error. If I put an alert or a redirect like this: $ (location) .attr ('href', ' link ');  It works, but I need to pass some parameters

$(document).on('click','[name="cobranca"]',function(){
        var tipo = $(this).attr('tipo-cobranca');
        var form = {}
        form['ids'] =  getCheckedValues($('.ck:checked'));
        form['tipo'] = tipo;
         $.getJSON('sendCobranca.php',
            {
                form: form
            },

            function(j){
                if(j){

                }
            });

        // console.log(form);               
    });