APEX

we have two application, one is 500, another is 600.
in application 500, english language application is 500, chinese language application is 501.
in application 600, english language application is 600, chinese language application is 601.

now i need from application 500 go back to application 600, i use following code to do that, english language is ok. but chinese language is fail. error message is "*Session state protection violation: This may be caused by manual alteration of a URL containing a checksum or by using a link with an incorrect or missing checksum. If you are unsure what caused this error, please contact the application administrator for assistance.*"


-- in application 500, "after submit process" region
l_url := replace(apex_util.prepare_url('f?p=600:4:'||apex_application.g_instance||':NEW_APPLICATION',null,2),':','|');
apex_util.set_session_state('AFTER_LOGIN_URL',l_url);
apex_custom_auth.post_login(l_login_name, wwv_flow.g_instance, apex_application.g_flow_id);