Even if you press folder icon and select file destination, it does not work. You have to type the destination manuallu.
What is your OS? and Version of Dreamweaver?
Can you send a screen shot showing the issue sao I can get a better understanding.
I cleared %appdata%.
The checkout wizard will use the eCart object of the cart display page that is open when you start it.
Whatever eCart object is used for the cart display page that is open in Dreamweaver when you start the checkout wizard is the cart object that will be used by the checkout wizard.