I need to sum a range based on the number on another cell
I use the following function to get that
=SUM(OFFSET(J45,0,0,L12)) (basically summing J45 thru J49 since cell L12
contains value 5)
I gives me the correct result from above formula when summing across rows.

However when I change that formula to sum across columns and changing the
same formula to
=SUM(OFFSET(J45,0,0,0,L12))
to sum across columns it gives me a result #REF!

What would be the correct formula to sum across columns.