first of all you can have a Look in the Logs. Most of the Problems you can solve with this.
I connected different Networks via th OpenVPN LAN-to-LAN service and it works fine. I use PSK to authenticate.
If there is the status: “VPN Process has not startet” it is mostly a syntax error of additional options. They appear in the Log.
Please post your configuration and Logs, because nobody will understand your Problem without.