Each change means that zone data files must be modified. Or at least use a tool to increment the serial number for you.
The syntax of zone data files lends itself to making mistakes.
The various configurations have been modified to reflect this.
Many BIND/DNS configurations are schizophrenic in nature - they may be 'masters' for some zones, 'slaves' for others, forward others and provide caching services for all comers.
Please take the time from a busy life to 'mail us' (at top of screen), the webmaster (below) or info-support at zytrax.