SUMPRODUCT() results in an error

Hi, Sir,

I am using SUMPRODUCT() to count how many cells with values. In column A, the values are:

Date
01/11/2012
#N/A

The function I used is:

=SUMPRODUCT(--(LEN($A$1:$A$5)>0))

Which resulted in an error. How can make this work?

Thanks a lot.