I have $Version -> "8.0 for Microsoft Windows (64-bit) (October 7, 2011)".
and I am trying to debug with workbench for the 1st time.
I follow the "Basic Debugging" screencast by right clicking on the (notebook file) in Workbench. Then I select (Debug as) -> (Mathematica 1) and the error message below is displayed.

Next I show where I have my Mathematica.exe.
In Workbench I selected the menu (Window, Preferences) and used the next image to try to ensure Workbench looks in the right folder, but I can't fix the problem.

Can anyone help?