[BusyBox] hush syntax

[mray at 360commerce.com]

I'm trying to use busybox 0.60.3 with uClibc .9.11 and I get the following error

hush: couldn't exec: [: no such file or directory

on the following block

#!/bin/hush

/bin/busybox md5sum -c /etc/usr.tar.gz.hash
while [ $? -ne 0 ]
do
/bin/busybox tftp -g -l usr.tar.gz -r /tftpboot/usr.tar.gz server
/bin/busybox md5sum -c /etc/usr.tar.gz.hash
done

I was under the impression hush had support for this syntax.  Am I incorrect in
my assumption or is my syntax bad (I pulled it from a bash scripting book)?

Thanks,
Matthew H. Ray