Update problem

Hi,
I have installed DreamweaverMx6.0,
and yesterday I've downloaded DWMX6.1 updater.
But I encountered a problem when I installed the
updater, when I selected the destination folder(where I
have installed DWMX6.0) and clicked ok, I met the
error message as follows:

This folder does not contain Dreamweaver MX.

I didn't know why this happened.
Please give some instructions.

Thanks in advance!