Work Week code throwing exception

Hi,

I am having trouble trying to get the work week tab enabled. I am using the code listed in the examples or custom view but it seems to be throwing an exception do to an undefined value. I am trying to have a work week tab that starts on Tue and ends on Friday. Can anyone help?

// work week tab
			
scheduler.locale.labels.workweek_tab = "W-Week";
scheduler.date.workweek_start = scheduler.date.week_start;
scheduler.date.add_workweek = function(date,inc){ return scheduler.date.add(date,inc*7,"day"); }
scheduler.date.get_workweek_end = function(date){ return scheduler.date.add(date,5,"day"); }
scheduler.templates.workweek_scale_date = scheduler.templates.week_scale_date;

I am getting this exception:

Uncaught TypeError: Cannot read property ‘0’ of null dhtmlxscheduler.js:146
scheduler.render_view_data dhtmlxscheduler.js:146
scheduler.update_view dhtmlxscheduler.js:107
scheduler.updateView dhtmlxscheduler.js:109
scheduler.setCurrentView dhtmlxscheduler.js:110
scheduler._click.dhx_cal_tab dhtmlxscheduler.js:87