RCA RTD255 System "dvd harman kardon player" Questions

harman kardon player will read blurays, however it wont read dvds. Any idea why? More than likely the lens that read dvd discs has failed. On blu-ray players, there are two (2) optical lens. One reads

...system through imput out put on vcr or dvd player as long as you have the out put coming out of tv then put the in put going to vcr or dvd but the thing is your remote will be your vcr or dvd

...harman/kardon) and I want to connect a cd player to it so I went to the local cash converters and got this RCA255 dvd receiver. Can I use this to play my CD's with my receiver or am I way off. Pls ...