I finally found out the solution to the problem myself.
Silly Errors are always the hardest ones to solve.
Same is the case over here.
As the Logon Dialog makes us all think that there's a great security issue associated with it, there isn't.
My mistake where i figured it out was that the report document uses the absolute full path of db included in the application.
So just modifying
ForEach myTable In repDoc.Database.Tables
myLogin = myTable.LogOnInfo
myLogin.ConnectionInfo.ServerName = Application.StartupPath & "\Db.mdb"
myLogin.ConnectionInfo.DatabaseName = Application.StartupPath & "\Db.mdb"
solved my problem.
I totally ommitted the Username and password and instead provided the path to the db.
Hope it might help someone else who is also banging his/her head
in front of the PC like i did for over a week....