Calculating days in between 2 dates (which have after 14 days issued date)

Dear All,

Can someone help me with this.

Eg.

A B C D
IssuedDate DateClosed OpenCase (for current month; 14 days after issued date) OverdueCase (14 days after issued date exclude current month)
25/12/2012 28/12/2012 ? ?

I also include the example sheet here.

Detailed description:
OpenCase value is (DateClosed - IssuedDate) - exclude Sundays & Holidays for current month. And OpenCase counted also already due 14 days after the issued date.
OverdueCase value is sum of OpenCase of previous month (before 25th of the current month).

The range of submitting case is between 26th (this month) - 25th (next month).

I had try many formula using WEAKDAY function but can get any value.

Please someone help me on this.

Let say:
Column
A B C D
1/2/2014 30/2/2014 Days Counted (B-A); but (B-A)>14days

So, the condition are:
1.count how many days (B-A)
2.if (B-A)>14, the Column C should have "1"
3.if (B-A)<14, the Column C should return ""(blank)
4.however, if B or A is more than 26th current month until 25th next month (eg: 26/1/2014 - 25/2/2014), more than that range, the value "1" should falls to next month data.
This record shall continuously month per month.

5.if Column A got a date, but Column B No, so Column C should detect Condition No.4 (above) and the value should be counting from the next 26/2/2014 (which should have "1" until Column B is inserted (have a date).
6. For Column D, it counts for the whole year which Column B still empty.

Sorry, not very good in explaining it. And the sheet I had upload before.

If the formula can't be in one, separate formula for each column would be good too.

Hopefully can someone help me with this problem.