Bind 9.1.3 classless delegation problems?

[Thomas Kiblin]

Hello,

I'm not a bind guru, I'm posting this for one of our admins trying to solve 
a problem.

We're running bind 9.1.3, and have been delegated a few class C's, we broke 
one of those C's up and re-delegate it down to one of our customers (half 
class C).

That customer is having problems while running his irc bots and servers, 
with A records not being found.

Talking to our upstream, they seem to think that a problem exist with bind 
doing classless delegation.

If they query our servers, everything is fine.  If they query outside 
servers, errors about no A records being found is very high.

HELP!

I'm about to lose this customer, but not sure how/where to go about 
troubleshooting this, they said there are no errors on their server, and 
I'm not sure what we can be doing to better trouble shoot this.

Any advice is welcomed!

One of the example IP's is 205.177.13.231, or .129-254.

Thanks!
Tom