Microsoft SQL Server Error 1475 when Mirroring
On your primary do you have a transaction log backup job running ? 

what would be happening is this db is larger by the time restores are completed the primary db would've had another transaction log backup taken, you just need to copy this transaction log backup to the DR and restore and mirroring should initialise.

other option is if you have enough disk space on your log drive you can disable log backups on the primary until you complete mirroring setup and re-enable it.

hope this help.