The tickRenderer is inside axis and not inside the rendererOptions.

HTML

<script language="javascript" type="text/javascript" src="https://bitbucket.org/cleonello/jqplot/raw/b5a7796a9ebf/src/jquery.jqplot.js"></script>

<script language="javascript" type="text/javascript" src="https://bitbucket.org/cleonello/jqplot/raw/b5a7796a9ebf/src/plugins/jqplot.dateAxisRenderer.js"></script>

<script language="javascript" type="text/javascript" src="https://bitbucket.org/cleonello/jqplot/raw/b5a7796a9ebf/src/plugins/jqplot.canvasAxisTickRenderer.js"></script>

<script language="javascript" type="text/javascript" src="https://bitbucket.org/cleonello/jqplot/raw/b5a7796a9ebf/src/plugins/jqplot.canvasTextRenderer.js"></script>

<script language="javascript" type="text/javascript" src="https://bitbucket.org/cleonello/jqplot/raw/b5a7796a9ebf/src/plugins/jqplot.highlighter.js"></script>

<div id="chart"></div>

CSS

#chart{
    width: 100%;
    height: 100%;
}

//jquery.jqplot.css
/*rules for the plot target div.  These will be cascaded down to all plot elements according to css rules*/
.jqplot-target {
    position: relative;
    color: #666666;
    font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
    font-size: 1em;
/*    height: 300px;
    width: 400px;*/
}

/*rules applied to all axes*/
.jqplot-axis {
    font-size: 0.75em;
}

.jqplot-xaxis {
    margin-top: 10px;
}

.jqplot-x2axis {
    margin-bottom: 10px;
}

.jqplot-yaxis {
    margin-right: 10px;
}

.jqplot-y2axis, .jqplot-y3axis, .jqplot-y4axis, .jqplot-y5axis, .jqplot-y6axis, .jqplot-y7axis, .jqplot-y8axis, .jqplot-y9axis, .jqplot-yMidAxis {
    margin-left: 10px;
    margin-right: 10px;
}

/*rules applied to all axis tick divs*/
.jqplot-axis-tick, .jqplot-xaxis-tick, .jqplot-yaxis-tick, .jqplot-x2axis-tick, .jqplot-y2axis-tick, .jqplot-y3axis-tick, .jqplot-y4axis-tick, .jqplot-y5axis-tick, .jqplot-y6axis-tick, .jqplot-y7axis-tick, .jqplot-y8axis-tick, .jqplot-y9axis-tick, .jqplot-yMidAxis-tick {
    position: absolute;
    white-space: pre;
}


.jqplot-xaxis-tick {
    top: 0px;
    /* initial position untill tick is drawn in proper place */
    left: 15px;
/*    padding-top: 10px;*/
    vertical-align: top;
}

.jqplot-x2axis-tick {
    bottom: 0px;
    /* initial position untill tick is drawn in proper place */
    left: 15px;
/*    padding-bottom: 10px;*/
    vertical-align: bottom;
}

.jqplot-yaxis-tick {
    right: 0px;
    /* initial position untill tick is drawn in proper place */
    top: 15px;
/*    padding-right: 10px;*/
    text-align: right;
}

.jqplot-yaxis-tick.jqplot-breakTick {
    right: -20px;
    margin-right: 0px;
    padding:1px 5px 1px 5px;
/*    background-color: white;*/
    z-index: 2;
    font-size: 1.5em;
}

.jqplot-y2axis-tick, .jqplot-y3axis-tick, .jqplot-y4axis-tick, .jqplot-y5axis-tick, .jqplot-y6axis-tick, .jqplot-y7axis-tick, .jqplot-y8axis-tick, .jqplot-y9axis-tick {
   ...

JavaScript

$(document).ready(function() {


    var lines = [[1334856823000, 2], [1334856853000, 1], [1334856883000, 0], [1334856913000, 4], [1334856914000, 13], [1334856943000, 16], [1334856973000, 23], [1334857003000, 24], [1334857033000, 36], [1334857063000, 14], [1334857093000, 1]];
    $.jqplot('chart', [lines], {
        seriesColors: ["#941B80"],
        title: "Snelheidsgrafiek",
        axes: {
            xaxis: {
                renderer: $.jqplot.DateAxisRenderer,
                //rendererOptions: {tickRenderer: $.jqplot.canvasAxisTickRenderer},//this is incorrect as tickRenderer should be outside rendererOptions
                tickRenderer: $.jqplot.CanvasAxisTickRenderer,
                tickOptions: {
                    formatString: '%R',
                    angle: 0
                },
                pad: 0
            },
            yaxis: {
                tickRenderer: $.jqplot.CanvasAxisTickRenderer,
                tickInterval: 20,
                min: 0
            }
        },
        series: [{
            markerOptions: {
                show: false,
            },
            rendererOptions: {
                smooth: true,
            },
        }],
        highlighter: {
            show: true,
            sizeAdjust: 3,
            tooltipContentEditor: function(str, seriesIndex, pointIndex, jqPlot) {
                
                return lines[pointIndex][0];
                
            }
        },
        
    });

});