Lookup & Index Match - Errors Returned

Hi Guys,

I am trying to set up a formula that checks a date is between 2 dates in a table and returns the corresponding column.

A	B	C
Start Date	End Date	Period
28/02/2009	27/02/2010	2009/10

The problem I am having is that if I search for 28/02/2009 it returns #N/A, this also occurs when I type 01/03/2009.

The dates in my table a populated by formula if that makes any diferrence and I attached an example for ease of reference.

Many Thanks