howto pstack running freeradius process

Hello, I am investigating one issue with freeradius 2.1.6 custom module and would like to get a stack trace of running process. pstack <pid of radiusd> fails with the following error: 23246: /usr/local/freeradius-2.1.6/sbin/radiusd '': opening object file: No such file or directory Could not open object file. The following commands was used to build the freeradius server: ./configure --prefix=/usr/local/freeradius-2.1.6 --enable-developer make make install Please point me to the right direction. Thanks in advance, George Chelidze