ajax - Calling WCFservice from ajax - NS_Error_failure

Question

I have a problem with my WCF service. I want to call it after some action. Here is ajax call:

$.ajax({
        type: "Get",
        async: false,
        url: 'service_adress/DoWork',
        success: function () {
            alert("Success");
        },

        error: function (jqXHR, textStatus, errorThrown) {
            alert(textStatus);
            alert(errorThrown);
        }
    });

Method do work should return string . When im putting service_adress/DoWork into adressbar in browser im getting correct response(< string>Something< /string>), but my ajax is throwing error NS_Error_failure. What is wrong here?