Could not turn on the WP_CACHE constant in wp-config.php. Check your permissions

Im Hosting at RAIDBOXES (https://raidboxes.de/) and want to use the Caching function of your plugin. The Hoster does not allow to have write access on the wp-config.php but he has a Accounting where i can add lines, that’s the reason i added the Cache Constant manually. i addes this line here:

define('WP_CACHE', true);

Now when i try to turn ON the Radiobutton “Enable page caching” it gives me the error message:

Could not turn on the WP_CACHE constant in wp-config.php. Check your permissions.

Is it possible to enable it in the database anywhere?
I also get every second Error logs like this here:

PHP Warning: Constant WP_CACHE already defined in ........wp-config.php on line 59

There is no Serverside cache wich could get in conflict with your Plugin (it is disabled).
There are two folder in the wp-content: cache, wpo-cache

Could you help me? I already had used your cache Feature on another page but i don’t remember what was the trick than to get it to work ?? or maybe with a update on your site something changed?

best robert

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