Countifs with Dates

I am trying to count the number of entries that fall in a certain state in a define range of dates. The state count works but there is something wrong with the date counts. I get a zero when I add the dates portion even though there is data in that range. N2 = 12/1, O2 = 12/31

=COUNTIFS(CLI_State,"CO",CLI_Date,">="&N2,CLI_Date,"<="&O2)

Counts by State Range
12/1/2011 0:00 12/31/2011 0:00
CO 0
MT 0
ND 0
SD 0
UT 0
WY 0
Grand Total