Follow the link below to install the most recent eID software version from your government.
https://eid.belgium.be/en/block/25/popup
Since it does work with the old ID card, it doesn't look like it's a hardware malfunction.
Due to the new ID card, it will probably be necessary to install the most recent eID software.
Next to installing the most recent eID software version from your Government/Bank; pay attention that the Chip on your ID Card is inserted correctly, for the Card Reader to be able to read the inserted ID Card.
There are older lay-out ID Cards and newer lay-out ID Cards in circulation.
The older ID Card lay-out, has the Chip on the front side.
The new ID Card layout, has the Chip on the back side present (refer to the picture above).
This could also differ per country.