php guestbook

hello, i want to include a php guestbook into my website... i´ve found a script which should write all the variables (i.e. email, message...) the visitor filled out into a textfile... but this don´t really work... it doesn´t write anything in the textfile... but when i type something into the textfile by myself, i can read it out... can someone tell me what´s the problem and how can i resolve it??? i am using the following configuration: apache webserver version 1.3.26 (windows) php version 4.2.1 windows 2000 pro thx for your help andreas