Problem with grub-install

[Matt Henley]

I have a system with two hard-drives connected to a Promise Ultra-100 
controller.  I have created a
raid partition that takes up most of the drives but have left room for a 
partition to be mounted as /boot.  I did this as my understanding is that 
grub cannot boot directly to a raided partion (/dev/md0).

In this case the partition for boot would be /dev/hde3 .  When I try to run 
grub-install I get the following
message :

/dev/hde does not have any corresponding BIOS drive

Any ideas what this means.  I am using kernel 4.1 built with support for 
the controller built into the kernel (not a module). It also has raid1 and 
reiserfs for the raid partition although I am using ext2 for the /boot 
partition.  It is the latest version of grub as found on unstable debian.

Any Ideas?  I am new to the world of grub.  Sorry if this has been asked 
before but I could not find it in the mailing list archives.

Matt