Hi Nadel.
This looks like Juniper only support CLNS under J and MX boxes. There is a command, clns-routing, you have to configure under the protocols isis hierarchy, but looks like is only supported under some 11.2 and 11.4 versions.
I have 10.4R7.5 and 11.2r2.4 junos without this command, and a 11.2r5.4 with it, maybe you will need to upgrade your mx. The release notes include this command from release 11.2R3.
Br
Alex.