A family member recently purchased me DVD box sets of both "Homicide: Life on the Streets" and "The Twilight Zone" while in New York. When I tried playing them on my DVD player (JVC XV-N55SL), the Homicide discs worked fine, but the Twilight Zone ones would not play and the screen read 'Region Code Error'. I tried a number of my other Region 1 DVDs and some are working fine on the player, but others are not.

Can anyone help me sort out this problem?