Cannot process audio

[LetitLoad]

Hi,

Basically, when I go to the audio tab at the top of the project window and select "process" so that I can do something like reverse audio for example, I click on the desired processing I want, but then nothing happens. I cannot reverse audio, I cannot pitch-shift, I cannot add an EQ at a particular point in a strip of audio. Basically processing doesn't occur. Has anybody got any ideas on how to fix this? Thanks in advance.

[Prock]

To start...
What Cubase version, what computer OS? Did it work before? Have you highlighted the audio event you want to reverse? Some screen shots may help us help you too.

Regards