C#计时器的计算编译问题

I have a windows form with a label, and a system.net timer called aTimer.

The timer is created in an external class like this:

// Create a timer with a 3 minute interval.
common.aTimer = new System.Timers.Timer(3000);

// Hook up the Elapsed event for the timer.
common.aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);

// Set the Interval to 3 minutes (180000 milliseconds).
common.aTimer.Interval = 180000; // 3000; //  
common.aTimer.Enabled = true;
mTimerRunning = true;

and in my form I run the code OnTimedEvent to kick off a background worker

I want to show on my label the number of seconds before the next action is taken.

I tried this but it won't compile:

lblStatus.BeginInvoke(new Action(() =>
                    {
        lblStatus.Text = "timer running - Check inbox in " & common.aTimer.Interval - common.aTimer.Elapsed & " seconds!";
                    }));

I have a compile error The event 'System.Timers.Timer.Elapsed' can only appear on the left hand side of += or -=

So what is the correct way to do this?

Ideally every tick of the timer I would update the label to show when the nxt run will happen.

lblStatus.Text = "timer running - Check inbox in " & common.aTimer.Interval - common.aTimer.Elapsed & " seconds!";