Get video with no audio sometimes when playing

get video with no audio sometimes when playing back DVD-Rs that i've burned, not sure how to troubleshoot this, i'm a bit of a noob when it comes to burning dvds... the lack of audio seems to occur when i'm burning a dvd that has more than one video on it. (i.e. A Scanner Darkly came out beautifully, put 5 episodes of Invader Zim on another disc, no audio whatsoever). oh and to burn the dvds i use Cyberlink PowerProducer v.3.07.3604.

any recommendations would be greatly appreciated.