Hi Philippe,
XP11.4x is obsolete and therefore we have also removed the dataset for this version. Look at here, we have announced this also in our FAQ:
It´s highly recommended to update your XP11.4x version to XP11.5x
You wrote, you have installed the XP11.5 dataset into your XP11.4x version - to solve this, it should be possible to re-install the XP11 - the setup should detect what is “wrong” and should download/overwrite the files, that you can use your XP11.4 version again. When not, please contact us again, then you must remove the files from the “custom data folder” to re-install the AIRAC files via the XP-setup.
Cheers,
Richard