I can’t launch patch 1.6.

First, the cumulative patch 1.6 has been released a long time ago, and it can be installed on any version (http://patches.ubi.com/heroes_might_magic_5/heroes_might_magic_5_1.06_rus_cumulative.exe). Second, the regular 1.6 cannot be installed on the Silver Edition; you need to install 1.5 first, and then 1.6 (this is most likely the problem. The cumulative patch installs on the Silver Edition without any problems).