By default, OCS agent don't send a full inventory each time you launch it. It only do a contact, check if there is something new from the server and give an inventory if something change on your computer. If nothing change, it will send a full inventory once a week (If I remember correctly, this is the default parameters).
If you send a full inventory, the database of the server will grow up very quickly (good for having bad performance) and the network traffic will be more important.
--force is not a standard parameters, this is for test, for debug or other state not in production.
For your problem, please send a full log in debug mode of your agent : it look like you have a certificat problem