regular expression grouping issue on attrs filter

[Ivo Vastert]

Hi,

I'm currently having a issue implementing a regular expression within the attrs configuration file.
When i try to group entry's within a regular expression the configuration is rejected:

For example:

This entry works:
Framed-IP-Address =~ /^172\.1[6-9]|2[0-9]|3[0-1]\.[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]\.[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]$/

This entry doesn't work:
Framed-IP-Address =~ /^172\.(1[6-9]|2[0-9]|3[0-1])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])$/

Does anyone know the correct syntax for grouping a entry within a regular expression?
It looks like grouping by () is not supported by freeradius?

We are using the following version:
freeradius: FreeRADIUS Version 2.0.4, for host i486-pc-linux-gnu, built on Sep  7 2008 at 23:35:34

Best regards,

Ivo Vastert