hi,all I have installed the CMU ns extensions followed by the guide. When I run the ad-hockey,the error of "can not load some library of Tk" is appeared. OS: RH6.2 NS:2.1b7a $rpm -q tk tk-8.0.5-35 I am stranger of PERL, do anyone know how to change the file ad-hockey or somethings I need to do to fix this error. THX for your replies! best regards! zhou jianxin [email protected]