The most common problem is that you cannot normally restore data created on a later version of SQL Server on an earlier version of SQL Server (eg: You cannot restore a 2008 database onto a computer running 2005 SQL sever).
If you have problems restoring data in Evopos you can try using Microsoft SQL Management Studio to restore the Data (This is a free utility that can be downloaded from Microsoft).
To Restore using Microsoft SQL Management Studio
•Open SQL Management Studio (normally select Start / All Programs / Microsoft SQL Server).
•Login using SQL Authentication, or use Windows Authentication if you are not sure of the connection details
•Right click the database name in the list of databases and go to "Tasks >> Restore >> Database..." Then select "From Device" and click the lookup button, then click "Add"
•Select the backup file you wish to use for restoring the data
•Select "Options", tick "Overwrite the existing database"
•In the "restore the database file as" box ensure the "Restore As" option is set to the same as the new database name eg: c:\Program Files\Microsoft SQLserver\MSSQL10.SQLEXPRESS\MSSQL\DATA\<NewDB>.mdf and "Log" to <NewDB>_log.ldf