In B6 the formula
=SUM(ADDRESS(B2,COLUMN(B6))&":"&ADDRESS(B3,COLUMN( B6)))
returns a #VALUE! error. The formula
=SUM(INDIRECT(B5))
returns the correct answer, when B5 contains
=ADDRESS(B2,COLUMN(B6))&":"&ADDRESS(B3,COLUMN(B6))
and returns the correct absolute address $B$9:$B$25, a range with some
numbers.
B2&B3 values may vary and the sum fomula is to be filled across row 6.

Am I missing something obvious?

Kevin