serious prolem, unauthorized user, very weird this time, a challenge!

I have a form_attendance app
user login: dilan
in group: dataentry

group dataentry has access … and insert right to form_attendance
has access to app_login

I log in with admin user and set the above, then log out.

I login with user dilan, login successful and user has access to form_attendance.
User dilan logout.
User dilan login in again: Unauthorized User

Tried several times deleting and creating user, getting the same response!!

Please help.