Countif

Hi wondered if anyone could advise what would be the best formula to use. I've been trying countif with no success.

I have a spreadsheet with a number of different columns
KILL DATE TIME LEFT TIME ARRIVED PH Overnight (Yes/No)
30/08/2013 15:30 17:00 5.48 No
30/08/2013 NR NR 5.41 Yes
30/08/2013 06:30 11:40 5.47 No
04/09/2013 05:35 07:20 5.29 Yes
05/09/2013 10.05 14:40 5.71 No

What I would really like is to be able to Count how many times a pH is less than 5.30 in August; pH is between 5.30 and 5.69 in August; pH is over 5.7 in August, same for September etc.

I have used the following for a simpler query:
=COUNTIFS('2013'!$a$1:$a$5,">=01/08/2013",'2013'!$a$1:$a$5,"<=31/08/2013",'2013'!$e$1:$e$5,"Yes"), which works fine but if i try
=COUNTIFS('2013'!$a$1:$a$5,">=01/08/2013",'2013'!$a$1:$a$5,"<=31/08/2013",'2013'!$d$1:$d$5,">=5.30",'2013'!$d$1:$d$5,"<=5.70") I have no joy.

i should mention that the '2013' referred to is the workbook that contains the data (trying to do the queries on a Stats workbook).

Anyone any ideas?

Many thanks

Chris