Unable to bind secure TCP listener to port 6514 There might be a problem with the certificate provided

I set up Secure TCP port 6514 in in Kiwi Syslog Server version 9.5.0.332.

I'm getting the following error :

Unable to bind secure TCP listener to port 6514 There might be a problem with the certificate provided

I'm using a self-signed certificate that I created  in IIS.

Why doesn't the error message tell exactly what is wrong with the certificate?

Could somebody suggest a solution or a workaround?

Thanks!