1st, verify that your project sequence and video match
Please NOTE that the PPro CS6 screen may look a bit different (I use CS5)
For CS5 and later, the easy way to insure that your video and your project match
See 2nd post for picture of NEW ITEM process http://forums.adobe.com/thread/872666
-and a FAQ on sequence setting http://forums.adobe.com/message/3804341
2nd, just what are you editing?
Read Bill Hunt on a file type as WRAPPER http://forums.adobe.com/thread/440037
What is a CODEC... a Primer http://forums.adobe.com/thread/546811
What CODEC is INSIDE that file? http://forums.adobe.com/thread/440037
Report back with the codec details of your file, use the programs below... a screen
shot works well to SHOW people what you are doing
For PC http://mediainfo.sourceforge.net/en or http://www.headbands.com/gspot/
For Mac http://mediainspector.massanti.com/
And, for the future, you need to supply more information when you ask a question - http://forums.adobe.com/message/4200840
With SD (Standard Definition) material, and HD Anamorphic, PAR (Pixel Aspect Ratio) will come into play. This article, and its links, go into more detail: http://forums.adobe.com/message/3456609#3456609
Not sure if you are beyond the PAR issues, and have moved on to something else, but that would be where I would start - if not.