alter system set log_archive_dest_2 gives LRM-00117: syntax error at ',' at the start of input

I am trying to setup a dataguard physical standby and one of the first steps is to add a log_archive_dest_2 parameter defining the data transport configuration.  The problem is I am getting a syntax error when I try to set the init parameter.

I look at my command and do not see anything wrong with my sysntax.

This is a Linux OS and the primary is an Oracle 11.2.0.4 RAC database.  Here is what I am trying to execute and the results I get after that:

SQL>  alter system set log_archive_dest_2='service=pstdby valid_for=(ONLINE_LOGFILES, PRIMARY_ROLE) db_unique_name=pstdby' scope=both;