Reverses not propogating

[Spaceboy]

Dear all,

First-time poster here, but know a little about bind so here goes.

Approx half of the class C reverse zone-files I administer appear to be propagating fine, in other words I can resolve ip's to hostnames from public nameservers.  However, from the same nameservers I am unable to resolve ip's to hostnames for the other half of networks.

They're all set up the same, have up-to-date serial no's, etc.

I'm stumped.

Any advice would be VERY much appreciated.

Details...
unresolvable ip: 217.68.67.130
resolvable ip: 217.68.64.10
Public name server: http://www.tracert.com/resolver.html

Many thanks,

Steve Mason