VB.Net 2003 with SQL server 2005 express

Hi,
I have an SQL Server 2005 Express database file that i want to use in VB.Net 2003 version.
Can any one help me?
I know i need to use the SQLConnection object but the connection string that i use is not good and i dont know how to fix it.
I have VB.Net project 2008 that works fine but the connection string is not working for me on the VB.Net 2003 project.

Any help will be good at this point.
Thanks

Please show us your ConnectionString that you have used, perhaps we can identify the problem