failed to resolve curpsinfo

I'm new to DTrace and found this really easy to install, but just a basic test probe isn't working

```
$ sudo dtrace -n BEGIN
dtrace: invalid probe specifier BEGIN: "/usr/lib/dtrace/node.d", line 56: failed to resolve curpsinfo: Unknown variable name
```

Running Ubuntu 13.04 with kernel version 3.8.0-27. Any help appreciated :)
