about HTTP Authentication

The following script doesn't work :( <?php if(!isset($PHP_AUTH_USER)) { Header("WWW-Authenticate: Basic realm=\"My Realm\""); Header("HTTP/1.0 401 Unauthorized"); echo "Text to send if user hits Cancel button\n"; exit; } else { echo "Hello $PHP_AUTH_USER.<P>"; echo "You entered $PHP_AUTH_PW as your password.<P>"; } ?> Error from IE browser: Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, steeven@kali.com.cn and inform them of the time the error occurred, and anything you might have done that may have caused the error. More information about this error may be available in the server error log. ------------------------------------------------------------------------ -------- Apache/1.3.9 Server at xxx.xxx.xxx.xxx Port 80 the result from "php.exe test.php3": WWW-Authenticate: Basic realm="" HTTP/1.0 401 Unauthorized X-Powered-By: PHP/3.0.14 Content-type: text/html Text to send if user hits Cancel button Logs from apache server: [Thu Jan 20 23:35:06 2000] [error] [client 172.18.76.177] malformed header from script. Bad header=HTTP/1.0 401 Unauthorized: c:/program files/apache group/apache/cgi-bin/php.exe Anybody can help? thanks! My system: win98 php 3.0.14 for win32 apache 1.3.9 for win32