Working on a Belgian quad and have worth prepared and chilled to 72-73f. Had 1 liter starter of WLP 500 prepared overnight with 0.25C of light DME and 1/8tsp of yeast nutrient. Yeast was fresh with Sept expiration date. Had also left yeast out sufficient time to reach room temp before mixing with the starter. Swirled occasionally to oxygenate. Pitched around noon on Day 1 and saw no activity in worth or airlock after 6 hours. After sitting overnight still no activity. Trying to figure out the error and what to do next. Any assistance much appreciated.