In excel the value of date of bitrth changes

Hi,
I use the Mail Merging & Macros to create Bio-Data's in Ms-Word of so many candidates & take their value like name. f'name , Date of Birth etc from a Excel Sheet. But i am facing the problem that as i am going to run the Macros, all the columns of excel sheet works very efficiently expect a column of Date of Birth. i used format cells & change the date of birth in format of 3/14/2001 without Asteriskk(*).

Date of Birth column has been change in Ms-word with a numeric numbers like 40322. In fact it remains same in the excel sheet.like 3/14/2001.
i face this problem not every iteration. sometimes it doesn't occurs. but problem is this i can't relay to this excel sheet infact it create problem while create other Bio-Data's.

i know while calculating age it change its format but it is optional, So it should not change the text cells. So i need a to operate a function which doesn't change the text cells. plz give me appropriate answer for this problem.
Regards

Hitesh Dev