[REBOL] Reading Binary data

[tim]

I want to open a file for read-only binary access.
Move to a specific offset in the file and read a
specific number of bytes:
I've tried this, but I'm doing something wrong

fp: open/read/direct/binary %TestBin.txt
skip fp 10  ;move to offset 10
buffer: read/part 10 ;error here, want to read 10 bytes
close fp

Advice Welcome!
Thanks
Tim