The media set has 2 media families but only 1 are provided

I got this error when restore database from .bak file.

why this error happen?

when you backup the database at that time you have not delete the existing path means you start a back up behalf of the previous one means your backup is divided in to more parts.

steps :
1)  you select all the related .bak file.

example here mydatabase name is test1. first i backup that at that time mybackup name is test1_17.bak. second backup i take at 18 and backup file name is test1_18.bak. now when you selecte restore database at that time you selected both this file.

rightclick on database –> task –> Restore –> Database

open one dialog box — now select fromdevice and add related files (test1_17.bak and test1_18.bak).

* when you take a backup at that time you remove the previous file.

Thnx.