It also has to be a 16 bit/44.1Khz wav file.
The speed the "Audio" CD was burned at can be an issue with some audio CD players, especially older ones. My audio CD burn speed standard is "8X", but SATA optical drives in newer systems will not burn that slow. The lowest most will go is 16X. I have a 10 year old JVC 5 disc CD player and it will not play (or will skip) audio CD's burned over 12X.
I do a lot of audio CD burning and I've had customers tell me my CD's play without problems but ones they have had burned at other places do not, and it was because of the burn speed.
I use Nero BurningRom as I have a bank of 5 CD burners and the Nero BurningRom will burn to multiple drives at the same time. Many other audio cd burners, including Sony CD Architect will not do that.