Running out of memory but not seeing excessive object allocation in Instruments

I have an iPad app that's crashing d开发者_Python百科ue to low memory. However, Instruments doesn't show any significant amount of memory allocated using ObjectAlloc - it stays under 1MB for the lifetime of the application. Leaks shows less than 1kB leaked over the course of the run. Memory monitor shows the free memory on the devices drop significantly with use, eventually dropping to the point that it's out of memory. Here's a screenshot from Instruments:

Instruments screenshot http://www.freeimagehosting.net/uploads/0758372561.png

I'm totally stumped. As far as I can tell, this basically says that as far as my app is concerned, I'm never using more than about 750kB, but that the device is still running out of physical memory, which is causing my app to crash/force exit.

I'm new to debugging memory issues with XCode. Am I measuring this wrong? Is there another way to see where this memory is going?

If you look at the Leaks row, you've got a whole lotta memory leaks all happening in a row. Check to make sure that you are releasing any objects that you allocated or that your classes own the references to.