You mean, you don’t see the MIDI fader in the Cubase Mixer (and in the MIDI track’s Inspector) moving?
This is normal, in the following circumstance (which is in fact the most likely case anyways 
)…
CC#7 (and in fact, any CC#) can be recorded either directly into the MIDI Part (where you can see it in the corresponding Controller lane in the MIDI Editor), or… it can be recorded as Automation (see MIDI Menu>CC Automation Setup).
It is only when using that 2nd option that you will see the fader move.