dsatish.. read this to know the real meaning of receipt number
click this url ( FROM BCIS site)
http://www.immigration.gov/graphics/fieldoffices/scnational/index.htm#D
For most applications filed at a Service Center, your receipt may look like this: LIN 99 001 50001. In this example, the LIN represents the Nebraska Service Center, where the application was initially received into the electronic system. Cases that are filed at or received by another Service Center but processed at the NSC will generally carry the designation of the originating Service Center:
LIN = Lincoln, Nebraska or NSC
EAC = St. Albans, Vermont or VSC
SRC= Dallas, Texas or TSC
WAC= Laguna Niguel, California or CSC
In the example above:
The 99 represents the fiscal year (October 1, through September 30) in which the case was received.
The 001 represents the computer workday in the fiscal year on which the fee was taken. SO, ITS NOT THE DATE THEY OPEN YOUR CASE. . ITS NOT ACTUALLY THE DATE THEY RECEIVED FROM FEDEX. ITS THE DATE WHEN YOUR CHECKS ARE CLEARED FROM YOUR BANK. SOME BANKS TAKE MORE TIME TO CLEAR CHECKS.
The 50001 represents the particular case number.
For cases with particular case numbers starting with a 5, electronic case status information is available (see Finding the Status of Your Case, below). For cases with particular case numbers starting with a 0, you must write to request the status of your case.
hope it helps you better understanding of the receipt no.