Bus LaoBu calculates the distance between your location and nearby bus stops. It then checks if any buses from those stops go directly to an MRT station, showing you the fastest walking + riding combinations.
Try increasing your search radius slider. If you're too far from a bus stop that connects to an MRT, or if you're already very close to an MRT, results might be limited.
We use LTA DataMall data for bus routes and stops. Distance calculations are estimates "as the crow flies" (straight line distance).