Forum:How can I link my carts?

I can't seem to be able to link my carts with the crowbar

I saw the page for the tunnel bore and it mentioned linking chest carts to pick up what it drills and it said to use the crowbar but as of yet I can't for the life of me get it to work. Im in singleplayer and maybe I'm being a tard and I need something else but its frustrating because I have a tunnel bore just sitting around now. Any help would be appreciated, or even alternative solutions to my problem would be immensely helpful