i've created a database connection to a mdf file for my app. When inserting data into the db, it didn't save the data between debug sessions. So i searched the net and found that when you specify the value "Do not copy" for the "Copy to output directory" property of the database, the db won't get overwritten between debug sessions. i did that and when trying to debug the prog i'm getting the exception "The underlying provider failed on Open.". when i specify "Copy always" for the db, i don't get this error. What's going on here? Please help.