An "Improper Song" error message indicates that the audio file attempting to be imported is not compatible. Be sure that the audio file meets the following specifications for importing:
WAVE: Sampling Rate: 44.1kHz, 48kHz, 88.2kHz and 96 kHz, Bit Depth: 16 or 24 bits
MP3: Sampling Rate: 44.1kHz and 48 kHz, Bit Rates: 32 - 320 kbps or VBR (Variable Bit Rate)
NOTES:
- MP3 files must be MPEG-1 Audio Layer 3 only. If you are unsure, check the conversion software you are using for this setting.
- Any file format, sample rate or bit depth that is not listed above is not compatible.
If you're certain that the audio file meets the specifications above, try repairing the audio file causing this error message to appear:
Repairing a Damaged or Unplayable Audio File
If the problem continues, try converting the audio file using conversion software such as iTunes:
How to Convert Audio File Using iTunes