Other applications may be interfering, see: http://help.apple.com/garageband/ipad/1.0/index.html#chsec12bae0
While you are recording a Touch Instrument, it is possible that audio events from other applications on your iPad can interrupt the recording. Take the following steps to minimize the possibility of interruption from competing audio events:
- Open the Settings app, and ensure that airplane mode is turned on, for devices that have an airplane mode.
- Make sure there are no alarms scheduled for the time you plan to record in the Calendar app or any other app (including third-party apps).
- Do not connect or disconnect headphones or other external devices during recording.
- Do not connect or disconnect the iPad from your computer while recording.
- Do not connect the iPad to (or disconnect it from) a power outlet while recording.
Also, you may need to extend your song sections.
Default track length is 8 bars. Need more touch the + sign at the right side of the scale near the top. A popup will appear that will allow you to adjust track length. I mostly use a microphone and acoustic string instruments, set the track length way out there (200) record my first track, dial the length back down to the end of the song. When you add tracks they conform to that length.
Hope this is what you were looking for.