How to deny accessing from OleDb Provider when Excel is opening?

Question

Hi all I am using Microsoft.Jet.OleDb.4.0 provider to obtaint data from Excel files. Here's the connection string and it works properly:

string conn = "Provider=Microsoft.Jet.OleDb.4.0;Data Source=source.xls;Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=1\"";

The problem is that I want whenever excel file was opened or to be using by another programs, OleDb provider wouldn't access to the excel files. I guess that I have to set some properties on Extened Properties. I have googled alot but it seems nothing about it.

anybody help me! thanks