It was designed for SQL Express (SQ), but should work with Compact SQL (CE).
I only run SQL Express because most of the time I need to run in multiuser mode.
Determining Database Mode
Double Click SambaPOS Logo to switch to window mode and check window title. At the end of the version number you’ll see one of these three suffixes.
TX: Text File Mode
CE: Single User Mode (SQL Server CE 4.0 is working)
SQ: Multi User Mode (SQL Server working)