I am using the following formula and it is returning a value of zero even
though onw of the rows meets the necessary condition and its value should be
4000.

=SUMIF(C5:C13,"<TODAY()-(30*Assumptions!$B$39)",E5:E13)

The values in column "C" are dates in the format "Nov-06". B39 is simply
the number "6" and the value in E5 is "4000". C5 is "Jul-02". What might I
have done incorrectly? Thank you in advance for your assistance.