Auto update formula when inserting cells upwards!!!

hi all,
i have a data sheet and i've added a simple sum formula like, "=sum(A1:A10000)".

now whatever data i add upto cell A10000. it gives me summation of all data.

but now i need to insert rows before first cell i.e. A1.

for example,
i've inserted 5 new rows before cell A1 in my data sheet. but still it shows old result only.

so can any one help me how to update data in this kind of data sheet???


thank you,


-Hardip