Not received any Syndic invoices but still asking to pay penalty

Hello,

After buying an apartment in brussels, the syndic of my building used to send me quarterly invoices for 2-3 quarters. But after that they suddenly stopped sending me for a year or so. Now their lawyer has sent me an official invoice with penalty at my correct address. The syndic now says that there was a mistake in the address and they used to send at my old address which I didn't received.

Now he is asking me to pay charges + penalty. I don't want to pay the penalty as its not my fault.

But he says that as an owner you should be responsible for all the invoices and if I didn't received any, I should have contacted them. I don't agree to this.

Whose fault is this? Mine or the syndic?

Thanks!