Restrict Entry into excel for dates more than 2 weeks in future

I am preparing a leave calendar for my team. The structure of the excel file is as follows:
1. Column A: Names of team members
2. Cell B1: 1st Jan
3. Cell C1: 2nd Jan
...
Continues till end of the year... one cell for each day of year.

Each member is expected to highlight the cells in rows corresponding to their names for leaves planned.

Example: If member "yyy" wants to take leave on 4/5/6 Jan, he will mark the cells as shown below.

My requirement is as follows.
Based on current date, if a member tries to update a cell for a date more than 2 weeks in future, it should give a popup about the restriction of doing so.

Example: Today is 3rd May. If any member applies for a leave for any date beyond 17th May, a pop should be given.

I hope someone can help me out in this.

Name	2016-01-01	2016-01-02	2016-01-03	2016-01-04	2016-01-05	2016-01-06	2016-01-07	2016-01-08	2016-01-09
xxx
yyy				Leave	Leave	Leave
zzz
aaa

Its working fine. Thanks.

However, I am unable to see the macro that you may have added. When I do ALT-F11, nothing is visible. :-(

Got it... Thanks a lot.

Ok. I have marked the thread as SOLVED.