okey, I have found the problem, but I don´t know what the problem is.
here we go: in SH3 save folder/data/cfg/careers we have a file whith name patrols.cfg. open it and scrol to ..."MerchantTonnageSunk=25199.000000"
it´s wrong. delete ".000000" and it´s working. But I can´t understand why