I'm making a 7-minute video presentation and it needs dubbing. It worked pretty well for the first trials that's got 4-5 mins/ But when I finished the whole video, while recording the audio, I waited for minutes but the is still unprocessed. What might be causing the problem? I invested so much time and effort for the audio and it did that. 

I'm not sure how long you should wait for it to process before cancelling. I would assume that you have made that decision by now.

If you had to cancel out of the Voiceover window before the processing was completed it is likely that the voiceover will not appear on your scribe. In this case you may need to get the overall memory usage of your scribe down before you make another attempt. There are many tips for doing this in the forum thread entitled TIPS to avoid crashes, freezes, failure to render or erratic behavior (2015) and the support article Crashing and freezing – VideoScribe desktop.

You may also wish to consider recording your voiceover externally in an application such as Audacity (free) and importing into VideoScribe as an MP3. See Record a voiceover for more information.