ᐅ What is the cause? Moisture problem with the panels

Dear forum members,

We excavated, backfilled with 50 cm (20 inches) of material, and have now placed the slabs on gravel. It appears that we have a moisture problem. Does anyone have an idea what might be causing this or has seen a similar case before? Many thanks.

Lime gravel
Not compacted
Godelmann Tetrago paving

That is normal and will be the case for the first period of time.

Thanks for the reply!
We have paved another area which was immediately "ready."
That's why we are uncertain.
May I ask if you are a professional in the field?