nero convert from APE to WMA

i'm trying to convert APE files to WMA, but half of the files that get converted are totally empty. SOme are obviously too small, like 5k. SOme you play and they just have no sound in them but the length appears to be correct.

i thought i downloaded the WMA encoder for nero (even though it had an option for WMA encoding before i did that) and it behaves exactly the same way after installing as before (yes i restarted nero burning rom and encoder)

anyone know what i could try?

i can convert APE to WAV no problem, or to mp3.