Uncaught TypeError: Cannot read property 'offsetWidth' of undefined when trying to change selected tab using jqxTabs

Question

Js code :

$('#observableTabs').jqxTabs({ width: 300, height: 170, position: 'top' });
        $('#observableTabs').jqxTabs('select', 1);
        EditOrAddActionModal = "Add";
        $("#AddPanel").jqxWindow("move", $(window).width() / 2 - $("#AddPanel").jqxWindow("width") / 2, $(window).height() / 2 - $("#AddPanel").jqxWindow("height") / 2);
        ClearAddForm();

Html :

<div class="form-group" style="float:left;">
                <label for="observableTabs" class="control-label">Observable:</label>
                <div id='selectAllcheckbox' class="pull-right">
                    tout selectionner
                </div>
                <div id="observableTabs">
                    <ul>
                        @{
                            foreach (var item in ObservableTypes)
                            {
                                <li>@item</li>
                            }
                        }
                    </ul>
                    @foreach (var item in ObservableTypes)
                    {
                        <div>
                            <div id="@item">
                            </div>
                        </div>
                    }
                </div>
            </div>

Console Error:

I can't figure out why this doesn't work thank you for helping