approve step is not working

Hi all

i have made simple workflow which is having the process and approve step.

i will explain you indetail about my problem in UWL in portal.

in MDM workflow there are two steps one is process step and second is approve step.

the process was assigned to one user called "xyz" and approve was assigned to another user called "abc".

now i configured the UWL completely according to the UWL config document.

now i logged into portal with user "xyz" then i went to the role called "workflow" there is that MDM workflow

task is displaying in the UWL list. there i have the button called (in the button) "ASSUME" but there is no button was displaying for "DONE" . what is the difference b/w ASSUME and DONE. but when i click on the assume button then again it is displaying next step button.

now i logged into another user called "ABC" for arroval. i went to workflow role there the task is displaying but there is no "APPROVE" button is displayed.

please help me out why the approve button was not displayed for the user "ABC"( approver).

for the user "abc" there is one button is displaying that is "next step" when i click this button then one error is displaying "page not found or displayed" error is getting.

Regards

Sunil