Wrong Data Pointer-XFS File system

Hi,
I am Using SuSe 10.0 with Xfs file system. I am working on a File system based project. During the initial research in On disk layout of File system , i found data pointer problem. I was not able to get the data location as per pointed by "absolute block no." in "xfs_bmbt_rec" extent pointers.

When i create any file in 0th (zero`th) AG in that case i am able to reach on proper location by using "absolute block no." pointer.

But when i create any file in 1st or in 2nd AG and so on. I never got the file data at the location pointed by "absolute block no.". I always found the file data before the the pointed address.

I am not getting any value in Superblock that tells me about difference in pointer location with actual data.

This value always becomes multiple of the AG number.

Please help to get out from this problem.

Is there any other calculation for finding the data locations.

I am right now consulting the Doument issued by SGI caleed "XFS file system Structure" 2nd Edition.

Regards

Sandy