I don't think it's a 'dud', as such - more that the type of plastic and Antex's level of quality control (
if they have any!
) is different to what we are accustomed to finding in the German and Malta-produced sets.
I've often read other people remarking that they think parts in Antex sets are of inferior quality, and a lot of collectors do avoid buying them because of this. I can't comment personally because I don't have any. I always felt the prices asked by the Argentinian eBay sellers was too high, especially given the evidence of so many disgruntled collectors. But then I would also have to factor in higher shipping charges than US buyers, so perhaps that makes a difference.
The Brazilian company Estrela also had a license to make Playmobil sets at one time. I've got some of those, and so far I have found them all comparable in quality to the German sets.