Hi,
Don't worry about the interview. They may have few questions about your documentation or application which requires further explanation. I don't think scheduling interview is usually to do the rejection. Go with peace of mind with all the documents that you submitted for PR process. I read in one of the thread, it will be simple and we don't need to think too much about that interview. Here is the thread which talks about the interview. Hope it will calm you stress
http://www.canadavisa.com/canada-immigration-discussion-board/-t482436.0.html
Think positive by saying that you have seen some movement on your application. All the best for your interview.