How to configure Sql reporting services with comodo SSL certificate

Im trying to configure my reporting services with comodo certificate. It works perfect with self signed certificate generated on this machine,but unfortunettly not with comodo cert .(I use Sql server 2014.)

1) in reporting services configuration manager I add comodo certificate in web service url node. Then im try to connect to generated link and my password is wrong (its correct for sure) .

2) following to this Configure SSRS for SSL i take the oportunity to log in but unfortunettly I get ERROR 503: server uninitialized.

Is there someone who had same bug and maybe can help with some magic tips?