Acrobat debugger. Script windows empty.

I have created a form in Livecycle Designer ES4, done a Preview and opened the file in Acrobat Pro. The window where the script is supposed to be is empty and so I cannot put in breakpoints and debug. At the bottom of the debugger windows it says "Unable to find the source for XFA ..."

The Initialise procedure in LCD

What could possibly be wrong here?