Why have I get kern.ipc.maxpipekva exceeded; see tuning(7) message ?

[KHalid Faith]

I use FreeBSD6.0

My server  give me an error as below

kern.ipc.maxpipekva exceeded; see tuning(7)

When I looked at its value as below

sysctl -a |grep kern.ipc.maxpipekva 
kern.ipc.maxpipekva: 16777216

How can I do about that ?

Thanks