Could it be that your scp doesn't return an error code?

In Windows, I'd check it as following:

>copy nul nul
        1 file(s) copied.

>if errorlevel 1 echo **

>copy bad args
The system cannot find the file specified.

>if errorlevel 1 echo **
**
[download]

As you can see, copy returns an error code >= 1 when it fails. Does your scp do the same?