D:\Quarterly Analyses\Scripts>perl File_rename_sw.pl   
Working on D:\Downloads\CI_Radar_watch\KeywordExposure-Box May SW.xls   
Working on D:\Downloads\CI_Radar_watch\KeywordExposure-Catalogic May SW.xls 
Can't call method "Activesheet" on an undefined value at File_rename_sw.pl line 130.