C/ODBC pls help

I am trying to setup C/ODBC for Navision 3.10 to access the database in MS Access for reporting purposes. At first try, I used a local connection and pointed directly to the database file of Navision and it worked. But when I try to use the linked tables later, I got an odbc-failure error. When I tried to redefine the link, I was told that the database is already in use. Then I remember that the successful connection, indeed was when I was the only one using the database. Does this mean that the C/ODBC driver needs an exclusive use of the database? Or is there something I did wrong? Please help.