mailRoutingAddress: attribute type undefined

[Robert Canary <phantom@ohiocounty.net>]

Greetings agian listers;

I am trying to import my migrate file of passwd to ldap, however, I am
getting the error sayin....well I posted below.

slapd[14549]: conn=0 op=0 BIND dn="CN=ROOT,DC=OHIOCOUNTY,DC=NET"
method=128
slapd[14549]: conn=0 op=0 RESULT tag=97 err=0 text=
slapd[14549]: conn=0 op=1 ADD
dn="UID=USERNAME,OU=PEOPLE,DC=OHIOCOUNTY,DC=NET"
slapd[14549]: conn=0 op=1 RESULT tag=105 err=17 text=mailRoutingAddress:
attribute type undefined
slapd[14549]: conn=0 op=2 UNBIND
slapd[14549]: conn=-1 fd=9 closed

I checked the schemas and the attribute is listed in the misc.schema. 
So apparently I am not understanding something..

Where to look to varify this attribute exists??  And if it isn't correct
what must I do to correct it?

thanks again advance :-)

--
robert