gauge install

hey guys,

quick question, i install the autotechnic s7 dimensional gagues yesterday. The install was successful except for one mnor thing. In the instructions it says to wire the positive lead to a wire that is hot when the parking lights are on. I wired them to a connection under the fuse box. I connected the gauge lead to the tail light connector beneath the fuse panel. My logic was that when the parking lights are on the tail lights are on as well. However, the gagues do not turn on when i turn on the switch. They turnon when i start the vechicle. Doe anyone know how to fix this problem or has done the same install and has been able to do it correctly. Any info would be helpful. Thanks