[SOLVED] Backend events error

Today I tried to update JEM v4.0rc1 in my local version of the test website. But the result was an error message:
JInstaller: :Install: Fout SQL Duplicate column name: 'emailacljl'.
In the attachment you find print screens telling you more.

P.S. I did not remove the old version 2.3.17, but just updated JEM.

This is other secondary efect of JEM reinstall (previous reply).
You can solved with this sql script:
ALTER TABLE `xxxxx_jem_categories` DROP `emailacljl`
(change xxxxx with your Joomla prefix)
This delete the new column of JEM pack 4.0b2 (before installed).
and try it again, install JEM 4.0rc1.

With your help updating from 2.3.17 to 4.0b4 has succeeded now. But I still have the problem I started this topic with. In the backend JEM > Events results in the error message:
Er heeft zich een fout voorgedaan.
1054 Unknown column 'places' in 'field list'

In version JEM 2.3.17 the problem does not exists.

You can see (and test) it on my test website:

I'm sorry, but we are patching the reinstallation error with previous version, but it has a solution.

In your case, It desn't apply the update: \administrator\components\com_jem\sql\updates\mysql\4.0b4.sql
You can run this sql script to make sure you have the update applied

In the last line adds 'places' in your register table.
ALTER TABLE xxxxx_jem_register ADD places INT NOT NULL DEFAULT '1' AFTER `uid`
Run these lines in your mysql, replace xxxxx for your Joomla prefix.

Thanks for your help with my JEM backend problems. At this moment the backend works fine.
But now I have problems with publishing the items. The JEM Simple List at my website (button Agenda) now says: Currently, no events are available. And the Calendar Module I defined in the column right is not clickable.

Hope you can help me with this problem too.

You can see and test it on my test website: www.kerkeninassen.nl/tefal/administrator/
Username: XXXXXXXXXX
Password: XXXXXXXXXXXXX

Please, don't publish credential of admin user in fpublic orum, better send PM (always) and with your permissions I have changed the password.
Let's me check and degug your case.