Listener not using sqlnet.ora file defined via TNS_ADMIN

I'm setting up a second listener for my DB.  I want this second listener to only accept encrypted connections. 

Here is how I attempted to do it:

- create $ORACLE_HOME/network/admin/secure directory

- in the secure directory, make links for the listener.ora, tnsnames.ora, ldap.ora.   Physically create a sqlnet.ora file and edit it with the appropriate encryption parameters.

- add the second listener to the listener.ora file.  In this second listener, use the ENVS variable to set the TNS_ADMIN variable to $ORACLE_HOME/network/admin/secure directory

Pretty simple right?  But it isn't working.  For some reason even though the TNS_ADMIN variable is set, the sqlnet.ora in the secure directory isn't be read.  Tracing the listener show that the encryption parameters aren't being set as expected.