Playability of Mini (camcorder) DVD-R in BD players

[jcs913]

My friend just bought a Sony BD300 and has a Sony DVD camcorder. He just tried to play the disc he made from the camcorder, which plays fine in his regular DVD player, in his Sony BD player. The player says that it cannot read the disc. Ironically, his regular DVD player is also a Sony and the camcorder has a Sony DVD-R mini disc in it. Any suggestions as to why??