Here is my situation :
I've made an audio installation for an outside happening, it's detecting motion and plays sounds with a random (code from mchobby with 6 sounds). The code compilation is good so it seems to come from the wave files. For the moment some of my sounds are recognized and played but some others are not.. I verified the files, I tried to do new exports, I tried different softwares (Audacity, Itunes, Garage Band)..
Equipement :
Arduino Uno
Wave Shield Kit (+ 4GB SDHC (FAT32))
Pir Sensor
9v powerbox
Sorry, I can't help as I do not own a Wave shield. I decided it was cheaper to just buy an Arduino Due for $12 from AliExpress and when combined with $3 SD card adapter it can play WAV files at higher quality without requiring a WAV shield. Of course it does require some wiring and the audio signal still needs amplification. (I just used a cheap PC speaker/amp)
This may not have any effect, but try changing the SD format to MS-DOS Fat16 instead of 32, and hit the reset button on the shield. Am new to all of this but have been tinkering with a similar situation- good luck!