Trouble with and isdn

I am trying to use the script to monitor an isdn line. We want to be alerted when the line comes up instead of the usual notification when the interface goes down.

The script has an invert option but when invoked on the Dialer interface I get the following message:

./ -H -C xxxxxx -n Dialer12 -i
Use of uninitialized value in sprintf at ./ line 500.
Dialer12:: 1 int NOK : CRITICAL

The invert option doesn’t seem to have an effect, the ouput is the same when run without the -i

The rub is that the script works fine when run against a serial interface.

Anyone have any sugesstion?

Thanks for your help

Why not use the check_snmp check instead?
The check can be used to see if some value matches for an oid. That oid I would assume is the interface status. If that value comes back as 0 (down) then that is a match and will not alert, but if anything else, then alert.