I re-wrote my example to clarify it even mo
A B C D E
1 4
2 a a 1 o
3 b a 2 p
4 c a 3 q
5 d a 4 r
6 e
7 f b 2 s
8 g b 4 t
9 h b 3 u
10 i b 1 v
11 j
12 k c 5 x
13 l c 1 y
14 m c 2 z
15 n c 4 k

In effect, the formula in B2 should give 'r', because C2=A2 AND D5=$B$1 (a
VLOOKUP in two columns at the same time, where one value (B1) is a constant).
The value obtained in B3 by dragging B2 should be 't' (C7=A3 AND $B$1=4).

z.entropic