crossfade function disabled


My knowledge of Cubase 6 is limited, the crossfade function stopped working abruptly in a bass editing session. When I select a piece of audio that needs a cross fade and drop the “audio” menu down “crossfade” is shaded grey (not an available function)

I’ve tried reassigning x as the key command but it does not work.

I’m stuck without the crossfade function. So I’m here for advice (when I open any other project and try crossfade it’s the same problem)

any advice?

Much appreciated