I see other posts with this problem but I just can't seem to solve it. I am new to d3 and am trying to load some data into a line graph, but i keep getting the error

Invalid value for <path> attribute d=MNaN,250LNaN,71.05263157894737LNaN,55.26315789473685

I have setup everything like in an example (which worked), but this isn't working for some reason. I am getting data back from a webservice as a list of the following form: Date=1/1/2014 NumberOfActive=1 (Example). I have tried using the parse functions but they don't really work. Here is my code:

var data;

        var margin = { top: 20, right: 20, bottom: 30, left: 50 },

            width = 1000 - margin.left - margin.right,

            height = 300 - margin.top - margin.bottom;



        function parseDateForViewing(d) {

            return d3.time.format('%b %Y')(d3.time.format('%m/%d/%Y').parse(d));

        }



        function parseDate(d) {

            return d3.time.format('%c')(d3.time.format('%m/%d/%Y').parse(d));

        }



        var x = d3.time.scale()

            .range([0, width]);



        var y = d3.scale.linear()

            .range([height, 0]);



        var xAxis = d3.svg.axis()

            .scale(x)

            .orient(bottom);



        var yAxis = d3.svg.axis()

            .scale(y)

            .orient(left);



        var line = d3.svg.line()

            .x(function (d) { return x(d.Date); })

            .y(function (d) { return y(d.NumberOfActive); });



        var svg = d3.select(body).append(svg)

            .attr(width, width + margin.left + margin.right)

            .attr(height, height + margin.top + margin.bottom)

          .append(g)

            .attr(transform, translate( + margin.left + , + margin.top + ));





        $.ajax({

            type: POST,

            url: Dashboard.aspx/GetActiveLoansData,

            data: '',

            contentType: application/json; charset=utf-8,

            dataType: json,

            success: function (thedata) {

                var d = thedata.d;

                data = thedata.d;



                var _len = d.length;

                var post, i;



                for (i = 0; i < data.length; i++) {

                    d = data[i];

                    var t = parseDate(d.Date);

                    var s = d.Date;

                    x.domain(d3.extent(data, function (d) { return d.Date; }));

                    y.domain(d3.extent(data, function (d) { return d.NumberOfActive; }));



                    svg.append(g)

                        .attr(class, x axis)

                        .attr(transform, translate(0, + height + ))

                        .call(xAxis);



                    svg.append(g)

                        .attr(class, y axis)

                        .call(yAxis)

                        .append(text)

                        .attr(transform, rotate(-90))

                        .attr(y, 6)

                        .attr(dy, .71em)

                        .style(text-anchor, end)

                        .text(Closed Loans);



                    svg.append(path)

                        .datum(data)

                        .attr(class, line)

                        .attr(d, line);

                }

            }

        });