Delegation question bind 9.1.1

[BRANCH DONALD]

My production bind server is bind version 4.9.7 which I will be updating to
9.1.1 the one problem I have is that under bind 4.9.7  I have one zone that
is being
delegated out to a "Reuters session server machine running an earlier 4.x.x
bind version"  everything works good. but when I try to do the same thing
under 
bind 9.1.1 the delegation doesn't work.  I kept the same file and just put a
$TTL at the top.   I was wondering if bind 9.1.1 has trouble talking to
earlier bind 4 versions.
I will give a copy of my zone file.

$TTL 86400
@ IN SOA  nudcnj10.rservices.com. root.nudcnj10.ny.ibj. ( 20 10800 3600
604800 6
00 )
@  IN NS   nudcnj10.rservices.com.

nudcnj10.rservices.com. IN      A       xxx.xxx.xxx.xxx
session.rservices.com.  IN      NS      ss1.rservices.com.
ss1.rservices.com.      IN      A       xxx.xxx.xxx.xxx


Donald Branch