Without knowing how the CD was burned, the format, the file format of the songs made, it's MediaInfo stats and the headunit.. impossible to answer any further.
Is it an audio CD or a data CD with audio files at the root (i.e. mps, wavs, etc.)?
If it's the latter, what file types are they? Are the unsupported ones different from the working ones? Where'd you get the songs? Maybe they have DRM on them if you purchased/leased the songs.
read the manaul to see what it accepts. look at whats different between the 2 that work and the others. may need to use a file converter or to find the files properly formatted