MDF file in windows application - after setup it become read only

Question

To All

I have generated an windows application. I have used .MDF file.
The project is working fine but when I have attached setup project to it and installed it. The permission of .mdf file get changed and become read only not able to write/update.

I am able to change the permission of .MDF file manually then after working fine. but is not current way of deployment 

So guide me what should I do now so I can read, write and update properly.

What code should i use/ technique should i use so I can do so.


I am using :

Visual Studio 2008,
C#.net 9,
dot net framwork 3.5 sp1
MDF FILE of Microsoft Sql server 2008 Express RC2