Srikanth,
Please get me a screenshot where you have entered 1208 as External number on left side and clicked on Start... If you had done that, there are 2 possible results
1) 0 Business partner found
2) Left side panel shows BP#2000008346
But the screenshot that you showed me before is something different.
Regarding documents- Under Legal control Export- Go to Display Existing documents and see if you can find the document. Make sure you are giving the Sales order# as Reference number.
Regards
Dhilipan