Can't use €20 promo code even when it should be eligible (DAV3 HS)

I’ve got a €20 promo code from finishing my account setup that’s supposed to be eligible for any purchase over €100, so I was going to use it when ordering the Deathadder V3 Hyperspeed but it’s rejecting the code for some reason. I’m assuming this is an error caused by the product being new or something along those lines. Would love for this to be sorted asap (since the code is only eligible for so long) so that I can order what seems to be an amazing piece of gaming equipment.