SQL Server express edition in windows application - error message -26 A network-related or instance-specific error occurred

I am very new to programming. I created a windows application. Used SQL Server database as the DB for it (My application is really a small one having just 2 screens and 2 tables). I have copied the db file in the folder with executable, and connection string is pointed to it. In the computer I created this application, ev开发者_JAVA百科erything works fine(VS 2005, C#, Windows XP). it works fine in different discs of same machine. Now, when I copy it into another computer (Windows 7 Home premium) and open the exe file, I get the error message Why?

Is it that I am using the wrong database? I wanted a mbile DB which can be deployed with the application, without installing it on the machine. Should I move to Access DB or SQL Server Compact edition?

Check the authentication for the user. on the other machine you may have different user credentials. Try to show your connectionstring that may give idea what is going on

Are you using the SQL Server Compact edition database file (sdf) or a standard SQL Database file (mdf). I have had a number of problems using .sdf files with Visual Studio Express.

Does new machine has MS SQL Installed?