[sirribbit]

Can someone help me figure out what I'm doing wrong.
I'm trying to autofill a column with a formula but it doesn't seem to be working right.

I have a column of numbers, cells A1=1, A2=1, A3=1, etc. (so the A column is all 1)
Then column B is various numbers, say... B1=1, B2=2, B3=3
These two columns are 20 rows. In cell B21 I have the total of all of column B
I want to put a formula in column D like =SUM(A1)-B21
Then I want to autofill the rest of column D with the same formula, changing (A1) with (A2) and so on as the column autofills. The problem I'm having is that it is also changing the B21, which I want to remain B21 for the entire column.

I hope this is a clear explanation of what I'm trying to do. Can someone help me figure this out. If you need more clarity, let me know. Thanks!

[edhicks]

Replace B21 with $B$21. You are using relative addressing where you need an absolute address

[sirribbit]

See... I knew someone could help. Thank you.