Did you set correctly the GamePath while using the Forwarder3DS app?Yeah I placed the the original ROM .nds file in the root of my Acekard's SD and the generated .nds file on my 3DS's SD in the _wfwd folder.
After loading a NDS game into the app, click it. You'll see the Game Path field. Did you set that to the root of your SD? If on the root, it should show only the name of the NDS file.
Like this: