Negative Cache won't go!

[Alans]

Hi everyone,

There is a website that was returning servfail but works fine with +trace.
AFAIK, negative cache default value is 3 hrs, and I haven't set
max-ncache-ttl, also domain owner says he used default TTL in his zone
files.
I waited for 1 day and the website didn't work till I restarted named.
Also I used rndc flushname domainname.com (with and without www.).

Is there any other way to solve this issue without restarting named? And any
clue why named isn't purging it?
I'm using Bind v9.4.2 on Centos 5.2.

Regards, 
Alans