I need to calculate amount of times certain code appears through my
worksheet between certain dates, e.g. how many times did DH (or KN) appear in
Sept)

KN 30/09/08
KN 10/10/08
DH 03/09/08
MG 03/09/08
PM 15/10/08
DH 14/09/08


I have tried dsum, sumif, array formulas, nothing seems to like dates