spring security-ntlm , no pop up asking username/password sometime

i experienced this and wonder any suggestion you folks can recommend. i'm using spring-security-ntlm 2.04. one or two users reported even though they set 'prompt for username and password' in their internet explorer. they are redirected to cannotlogin.jsp rather than seeing pop up asking for username and password.

   <security:http access-denied-page="/cannotlogin.jsp"
     entry-point-ref="ntlmEntryPoint" 
     servlet-api-provision="false" 
     >

do you think is this spring-sec开发者_StackOverflow中文版urity-ntlm problem or internet explorer?