I've tested with a new startSSL certificate and also with your SSL certificate. All is working as expected apart a small warning which has been fixed by updating the phpseclib library used by i-MSCP. I also rewritten the SSL certificate interface (will be available in next release) because I was not happy with the old one (I'm still not happy anyway...).
The only thing that I've not used is your CA bundle. I generated my own CA bundle using the proper files from the StartSSL site.
Below, you can see some screens in which you can see that your certificate is working.
For the rest, I'll send you a PM to give you the exact instructions.
