Panasonic "Audio not supported"

I have a Panasonic DMP-BDT120 Blu ray player connected via an optical toslink cable to an amp and then via RCA to a Denon RCD M40 Hi Fi using 2 speakers. Many Blu Ray discs work faultless, however one "An idiot abroad" states audio not supported and has audio for the pre program and once the episode starts produces no audio and "X Men" states no audio and plays audio fine, (both discs play in an xbox) I know I have a lot of variables with using a small Chinese amp and HiFi but I am hoping i'm not the only one that has had this issue, can anyone help me to rectify this audio issue?