not a valid win32 application

[ptz]

I'm compiling and running the following test script:

OutFile "hello_world.exe"
InstallDir $DESKTOP\hello_world
RequestExecutionLevel user

Page directory
Page instfiles

section ""
SetOutPath $INSTDIR
#File hello_world.nsi
messageBox MB_OK "Hello world!"
sectionEnd

If I uncomment the line "File hello_world.nsi" everything is OK, but as is it produces a "... is not a valid Win32 application" error in runtime. I am a complete beginner both in NSIS and in Windows, and would like to know why this happens. Or at least how to stay away from this problem.

Thanks.