Decode an old mp3, originally recorded in June-50

Hi, maybe OT.
I have tried to decode an old mp3 with various settings to wav with mad, and
the decoding seems to work fine.

But when I try to burn the wav with k3b, k3b says "wrong format". madplay -v
-i -m --output=wave gives "Layer III, 64 kbps, 22050 Hz, single channel, no
CRC, 7095 frames decoded, -7.4 dB peak amplitude, 0 clipped samples"

Does anybody have any suggestions about what options I should choose when
decoding. I would like to have it in wav.

Or maybe I should look in my k3b settings for this particular file..?

Best regards
/jrx