Sumproduct with datediff

I have a spreadsheet which records the history of incoming drawings and outgoing comments.

Column A: Drawing number
Column B: Issue number
Column C: Date rec'd,
Column D: Date comments returned

I need to generate a series of reports and have used the following formula

How many drawings rec'd in 2011:
SUMPRODUCT(--(YEAR(Record!C4:Record!C30)=2011))

How many drawings rec'd in January 2012
SUMPRODUCT(--(YEAR(Record!C4:Record!C30)=2012),--(MONTH(Record!C4:Record!C30)=1))

How many drawings rec'd in January 2012, issue 1
SUMPRODUCT(--(YEAR(Record!C4:Record!C30)=2012),--(MONTH(Record!C4:Record!C30)=1),--(Record!B4:Record!B30=1))

Question:
I now want to check which ones have had comments returned within 14 days. Was trying to use datediff between Column C and Column D and added into the example above.
i.e. How many drawings rec'd in January 2012, issue 1, comments returned within 14 days

Can anyone help me either on how to add into my existing formula or suggest an alternative approach?

Thanks