Tahoe RSE no sound while in DVD mode

[Cfred]

I have a 2004 Tahoe, with a OEM Boss entertainment system. I also have the OEM Panosonic DVD player. We have had to replace the amp and DVD player this last year but everything was replaced with OEM parts. I get sound through speakers while in AM, FM, and CD but nothing in RSE. I know the DVD player has to be on and playing a DVD which it is, but when you flip source to RSE nothing comes out except some crackling. The wireless OEM headphones work and so does the DVD remote. I also tried switching it to just AUX and plugging in my iPod with audio cables and also nothing but crackling. What do I need to do?