Paper get rejected despite positive recommendations from both reviewers I have submitted a paper to an IEEE conference before this. I received a rejection today despite the fact that, both reviewers recommend to accept my paper.

The reason for rejection is not mentioned at all in the email. I try to analyze the reason and from my point of view:


The paper is not out of the conference's scope. If my paper is out of scope, it should be rejected at the first place without sending out to be reviewed.
Both reviewers recommend to accept my paper.
The conference should have not received too many papers. This is because the deadline for submission has just been extended to 10 Nov. In other words, they continue to accept submission of papers at this point. 


I was really surprise after I read the following email:


  Dear xxx:
  
  Unfortunately, your paper xxx for xxx has not been accepted for
  publication. We hope that you will find the reviews useful when
  revising your paper.
  
  The reviews are below or can be found at xxx.
  
  ======= Review 1 =======
  
  *** Originality: New or Novel contribution Strong Accept (10)
  
  *** Technical Contribution: Technical/Scientific Contribution, also consider papers that contributes to development of applications.
  Accept (8)
  
  *** Significance of Topic: Relating to knowledge contribution &amp; conference scope (relevant to Science, Engineering &amp; Technology)
  Strong Accept (10)
  
  *** Presentation: Clarity and Organisation of Content (Includes Language &amp; Formatting) Accept (8)
  
  *** Recommendation: Overall view and recommendation Strong Accept (10)
  
  *** Detailed comments: What are the major issues addressed in the paper? Do you consider them important? What are the major reasons to
  accept or reject the paper? Comment on the degree of novelty,
  creativity and technical depth in the paper.[Be brief.]
  
  Please provide detailed comments that will be helpful to the TPC for
  assessing the paper, as well as feedback to the authors.
  
  The paper was reporting an original findings by the authors based on
  their simulation. xxx. I reckon it is of sufficient quality for the
  conference.
  
  ======= Review 2 =======
  
  *** Originality: New or Novel contribution Accept (8)
  
  *** Technical Contribution: Technical/Scientific Contribution, also consider papers that contributes to development of applications.
  Accept (8)
  
  *** Significance of Topic: Relating to knowledge contribution &amp; conference scope (relevant to Science, Engineering &amp; Technology)
  Accept (8)
  
  *** Presentation: Clarity and Organisation of Content (Includes Language &amp; Formatting) Accept (8)
  
  *** Recommendation: Overall view and recommendation Accept (8)
  
  *** Detailed comments: What are the major issues addressed in the paper? Do you consider them important? What are the major reasons to
  accept or reject the paper? Comment on the degree of novelty,
  creativity and technical depth in the paper.[Be brief.]
  
  Please provide detailed comments that will be helpful to the TPC for
  assessing the paper, as well as feedback to the authors.
  
  Good paper and well written. Easy to understand. xxx.


I replaced some of the reviewers' comments with 'xxx' because it will reveal my unpublished works. Please believe me when I say they are all positive.

Has someone been in this situation before? What is the possible reasons for rejection?
This is a perfectly possible result.  The reviewers' recommendations are just that: recommendations.  The conference's scientific committee has the ultimate say over whether a paper is accepted, and they do not always follow reviewers' recommendations.

There may be quite legitimate reasons for a paper to be rejected despite positive reviews.  For example:


There might be an abundance of high quality submissions on the particular topic you submitted on (even if the deadline was extended because they didn't get enough submissions in other areas).
There still could be a scope issue.  Yes, a paper that is clearly out of scope should be rejected before it goes to review.  However, if the committee felt it was at the margins of acceptable scope, they might send it to review but ultimately reject it because the reviewers' comments weren't sufficient to overcome the scope problem.
The conference reviewers were generous.  It is hard to interpret the meaning of the reviewers' scores without seeing the distribution of all scores.  It is possible that the reviewers were really "nice" and scores tended to be high for everyone.  It is quite difficult for many people to give a negative decision when they know that someone else is going to see the result and be affected by it, so scores can tend toward the positive, and rejection recommendations may be rare. 
There was some kind of rule preventing them from accepting it (This should have led to rejection before review, but it could have been missed.  Of course, they also should have told you the reason if this were the case).


You are correct, however, that this is a fairly unusual decision.  I think you ought to follow up and ask for clarification.  It would be helpful for you to know the reason for rejection, and there is always the chance that there was some kind of clerical error, as well.