11/01/06 10.0
11/02/06 10.0
11/03/06 10.0
11/04/06 10.0
11/05/06 10.0
11/06/06 10.0
11/07/06 10.0
11/08/06 10.0
11/09/06 10.0
11/10/06 10.0

the above range is placed in B6:B15

cell B3 contains 11/01/06
cell B4 contains 11/05/06

doing a simple average(C6:C9) produces 10
placing a conditional average if cells B6:B15 are between 11/01/06 and
11/05/06 , average corresponding cells in C6:C15 as in expression

{=AVERAGE(AND(B6:B15=B3,B6:B15<B4),C6:C15)} produces an incorrect
result = 9.09

why is that ?

cheers,
deano