some databases have not been vacuumed ...

[FM <dist-list@xxxxxxxxxxxxxxxxxx>]

Hello after a vacuum full analyse I received this  :
WARNING:  some databases have not been vacuumed in 1805294030 transactions
HINT:  Better vacuum them within 342189617 transactions, or you may have 
a wraparound failure.

I read that it's because i do not vacuum DB very often.
Now I vacuum every night but the warning remains.
How can I get rid of this ?

Thanks !