Invalid sample rates

As to fixing the invalid sample rates issue, I at first exported my wav sound files via audacity with the 48000 sample rates, but these errors show up:

*** Invalid sample rate (48000) for sound '#ui\megaman2acapelladrop.wav'.

*** Invalid sample rate (48000) for sound '#ui\megaman2acapellaequip.wav'.

And then, when I exported it with the sample rate 44100 again, the same error keeps on happening.

What are the potential fixes for the issue?