ATM problem with Cisco 6400

[Abrams, Chris]

I am running into a problem with our Cisco 6400s. I have a NNI between a BPX
and 6400. It only allows me to use up to 8 bits for VPI.  The ATM spec
states that 12 bits for VPI over NNI connection.  

I do the following on the 6400:

interface ATM5/1/0
 description oc3 to BPX
 no ip address
 no atm auto-configuration
 no atm ilmi-keepalive
 atm nni

LAB1-6400-1-NSP(config)#int a5/1/0
LAB1-6400-1-NSP(config-if)#atm max
LAB1-6400-1-NSP(config-if)#atm maxvpi
LAB1-6400-1-NSP(config-if)#atm maxvpi-bits ?
  <0-8>  Configure maximum number of VPI bits


Has anyone run into this problem?
Is there a new version of IOS that will support this?


Thanks