How do I sum a column of numbers but only if the cell in the adjacent column
contains a date within a certain range, also ignoring any #N/A errors

e.g.

A B
1 1st October 2007 1
2 31st October 2007 2
3 22nd October 2007 #N/A
4 1st January 2007 3
5 22nd January 2007 2

So if wanted to sum the numbers in column B, but only including the numbers
where the corresponding cell in column A is between 1st October and 31st
October (note column A is in date format), and ignoring the #N/A errors. The
answer here would be 3.

Thanks

John