dvd will not play in player

[mork55uk]

can any one please help?
i have a dvd back up on a 4.7gb disk that play's in my home dvd player fine.
i used clone dvd and i have tryed copy2dvd and both programmes copy the disk with no errors reported the only problem is my new copy will not play in the home dvd player. i have tryed using the same type and brand of disks.
i have noticed that even through the main folder video_ts file are the same size on the 2 disk's the new copy has at least one video_ts smaller.
i am using a nec 1300 if that helps.
thanks...