Peopple keep misunderstanding what makebootable does. What you needed was probably writembr instead.
The boot process with a BIOS is in two steps:
- The BIOS reads the first sector of the disk, and runs whatever code is there. For Haiku there are 3 ways you can get code there: installing bootman, using writembr, or creating a new MBR partition table from DriveSetup.
- That code finds a partition to boot and loads the first sector of the partition. BootMan lets you chose which partition, while writembr and the code installed by DriveSetup will just pick the partition currently marked active. You can mark a partition active in DriveSetup when you create it.
The code in 1 can be replaced with many other versions: the one from Windows, from FreeBSD, or another boot manager such as Plop or Smart Boot Manager. The code in 2 is specific to Haiku and is the one that is installed by makebootable (but also by Installer, so you should never need makebootable if you use Installer).