I can't record my voice using GarageBand, but can still record instruments I installed v2.0.7 of GarageBand to my iPad a few months ago. 

I've just tried recording my voice using the audio option and it told me I did not have enough free storage. However, I can still record using the other instruments provided by GarageBand, so space doesn't seem to be the issue.

How can I troubleshoot this to determine why I can't do a voice recording using GarageBand?
I'm assuming the Instruments are already-loaded samples, you're just lining up along a track, or as a midi track to fire single note samples.  

If so, that requires very little additional storage - the samples are already there, it just needs to remember what order they go in. 

An actual audio recording, on the other hand, is going to eat about 5MB data per minute, mono, or 10MB/m stereo.