If you receive the error message:

MPRINT(RDSLOGFILEPOLLER):   proc sort data=lib1.logFile;
MPRINT(RDSLOGFILEPOLLER):   by pathName;                
ERROR: Variable PATHNAME not found.                     
ERROR: Variable PATHNAME not found.                     
ERROR: Variable PATHNAME not found.                     

... the reason might be that there has been an error in the run, that initialized the log database.

To solve this problem delete all data sets from the log database and restart Yalan.