Is it possible you have an ATmega1284P on your Sanguinololu? USBasp is known to be limited to chips with 64k Flash or less.
That said, using a programmer, you can upload a firmware directly, without bootloader. Up to the 64k limit, even on bigger chips.
That said, using a programmer, you can upload a firmware directly, without bootloader. Up to the 64k limit, even on bigger chips.