I have a 2008 van. If your wiring is similar to mine, you have a loose connection.
My picture below has the van side wires on the right and light wires coming in from the left.
The Black van wire is Ground and should connect to the White Wires from the light.
The Green Striped van wire is Power and should connect to the Black wire from non labeled side of the light.
The Black Striped van wire is Door Open (Valet) and should connect to the Black wire from JUNCO labeled side of the light.
In addition, your lights should turn on when the dimmer switch is turned completely counter clockwise until it clicks.