Oracle Message ORA-07221 - slspool: exec error, unable to start spooler program.

ERRORslspool: exec error, unable to start spooler program.
CAUSEExec failed when starting line printer spooler command. Likely that either the default line printer command, or ORACLE_LPPROG, is incorrectly set.
ACTIONVerify default line printer command and ORACLE_LPPROG are set correctly. Set ORACLE_LPPROG to working line printer spooler.