Content of label does not refresh

I am a novice to AJAX.
I have a label control and a AJAX Timer control in a UpdatePanel.
The interval for the label is set to 10000 ms.
The timer tick event handler has a statement to change the content of the label control.

This is the statement in the timer tick:

Label1.Text = "Content updated on " & DateTime.Now.ToString()

When I browse the page, the content of the label control does not refresh.
There is a message at the message bar that reads:
"Done, but with errors on page."


Did I missed out anything or did something incorrectly?

Hope someone can advice.

Thank you.