Color problem when rhodium plating 18WG

Hello all,

I need your help. My problem is the rhodium plating that is done on
18 K white gold jewelery comes our bright steel colour, hwen compared
to jewelery from Hong Kong and China where the rhodium is bright
white. Have tried all possible methods, but no sucess.

I use Legor RH2 W.

How does one get the silvery white in rhodium ?