I must transfer one database from a first server to a second server. I received the Mydatababase.bak file from the first server, this file I copied to the second server in the folder

C:\Program Files\Microsoft SQL
 Server\MSSQL11.SQLEXPRESS\MSSQL\Backup\Mydatabase_BACKUP.bak

In the RESTORE DATABASE Dialog of the MSSQL Server I receive the following error now while selecting my Backop file

    C:\Program Files\Microsoft SQL      

     Server\MSSQL11.SQLEXPRESS\MSSQL\Backup\MyDatabase_Bak.bak 

    : Family count:2 : Missing family sequence number :1 

What does the error mean? What information is missing now ?