Windows Networking Password Change

Running Winnt4.0 Sp3 want to force users change password @ logon. I enforced it on NT
When user logs on to PC in win98. They are prompted to change password. But when they try and change it Win98 says access denied
to any type of password used. Also thier able to bypass by canceling or hitting escape. Any ideas why it comes up with access denied?
or why it lets tem bypass it?