Ali
What I will say here is not an answer really, but i'm afraid it is the truth. No one should share an Excel file. Excel is not a sharing application, databases generally are.
I suspect what is happening here is that several people are making changes at the same time and therefore only the last wins from the chnage history.
I think you will find no one on this board who would have experience of sharingan Excel file as it is such a bad idea.
Sorry that sound so lame
Regards
Nick Hodge
Microsoft MVP, Excel
Southampton, UK