Can't Enable SRTP in Asterisk menuselect

I worked through the steps found here: voip-info.org/wiki/view/Asterisk+SRTP
for adding SRTP to the Asterisk 1.8.x builds.
The steps up to and including the srtp library install all gave no errors and completed fine, including the install step.

When I go to build Asterisk using make menu menuselect, the resources line tiem has the following line:
XXX res_srtp
The bottom of the screen says:
Secure RTP (SRTP)
Depends on: srtp(E).

I have searched all menu items and can’t find an option that allows this to be enabled. (So I can’t get it to build with srtp).

Any ideas what I’m doing wrong?
I am running Fedora 11.
I saw no reference to this in the forums.

Did you install libsrtp (and/or associated -dev packages) before running ./configure ?